Definitely all of the above (particularly get a thorough vetting from someone you trust - £250 now is a lot cheaper than £2k plus long term vet bills/time out for lameness/sadness all round when it doesn't work out...) and also, from my own/friends' experiences:

*As with cars, sometimes you can identify a 'dealer posing as private seller' by calling/contacting about 'the horse' without giving further details - so don't click through from an ad - either email separately or telephone. If they have more than one to sell they may either mis-guess, or press you for more details at this point as they won't be able to immediately know. Doesn't knock them all out, but may help reduce the number

*Turn up early for a viewing (up to an hour before time - makes it more difficult for someone to 'calm' (ahem) an 'excitable' (for which read potential lunatic) animal prior to you sitting up.

*Insist on hoof-picking/tacking up/un-tacking/sweat scraping yourself. Always run your hand all over to see if how comfortable the horse is/if there are unexpected sore spots or lumps and bumps.

*If a competition horse, look up the relevant websites to see what the results are like

*If you can, have the current owner agree to either allow you to take them in a competition (even if only something well below the level the animal is billed as capable of) or for you to view the owner competing them in the discipline in which you want to use them (I have seen an ex-top flight eventer go beserk on the hunting field for e.g., only to be a complete lamb when taken home early with one companion (It was being sold as 'an ideal hunter'.... Ditto a few alleged 'show-jumpers' not entirely coping with a course that wasn't built at home).

*If you are interested in them for jumping then push up the height to where you feel comfortable, and then have them add in a v.low jump (so work up to 1.30m then drop back to 70cms for e.g.) - if they treat both the same way and you like the horse's way of going, hang onto them!

*Don't be blinded by a looker

Very best of luck - hope you find the perfect beastie. There's nothing like that feeling when you suddenly realise you have a companion on your adventures.

Also, yes - forget about price, it should be immaterial when it comes to questions, although I would be wary of someone claiming a sub £2k horse has Grand Prix potential...

Pleasure! Yes, the passport should list the previous owners.

It won't necessarily list all of the previous owners.
Take someone with you when you view the horse. Someone experienced who is impartial. If you trust your instructor, then that is a good start.
Word of mouth is also great to hear good/bad things about a horse.

I'm no expert on buying horses, but when we bought ours, we found that askin our instructor and everyone we knew proved very useful. As it happened, our instructor knew of some horses that we're potentially suitable for us. She knew the horses and the owners, So was able to reassure us as to why they were sale, what they had done recently etc. It also proved useful as our instructor was really able to help us with the horse we did buy. As it happened, we bought a horse with a previous injury, but we were able to gain a lot if I do about it, as well as keeping the same vet on.

Ask all your questions in front of a third party to act as witness to the answers and keep a copy of the ad and any written correspondence with the seller.

From the things you mention:

• Yes ask about medication and also past medical history, injuries, illnesses, time off work, allergies, laminitis, colic and anything else you can think of.
  
• viewing twice is reasonable but very good horses sold at reasonable prices may go at the first viewing - be aware it's a risk you take.
  
• you should ask to see the horse trotted up on the hard, then the owner should ride (do not get on anything the owner refuses to ride), he/she should show the horse in walk, trot canter, a couple of jumps (revise as necessary depending on what you want the horse for), then you should ride in the arena. If the horse appears suitable ask to hack it, even down the road and back is useful as you can check it's not nappy. Get someone to start a car and drive past if you can't try the horse on the roads directly. Second viewing you should ride from the start. Get your instructor to come along for advice or videotape the ride.
  
• I've never done this but why not. I've mainly bought competition horses so their records give out quite a lot of information about past history.
  
• do not buy anything without a 5 stage vetting. A cheap horse is as expensive to treat or retire as an expensive one so a vetting is a must.
  
• ask the seller if he/she is the owner, ask them if they are a dealer. If they lie you have a case against them.

Definitely do not get on a horse until it has been ridden by someone else first. you want to see it being ridden both in the school and hacked out on its own, in traffic.

Before you arrange a visit ask what facilities there are for riding the horse and whether there is someone to ride it before you get on. A field is fine as far as facilities go as long as you can walk, trot and canter but don't let anyone sell you a horse unridden. If the owner won't get on they should arrange for a friend to get on or pay a professional - never get on a horse you have not seen ridden. There are some very unscrupulous people out there!

Other little tricks to look out for: when you take the horse for a hack do not let the owner walk by the horse, they are giving it a lead! Any people should stay at the yard, if you cannot go for a proper hack walk the horse out the gate, back to the yard, back out the gate and back home to see if you can provoke a nappy reaction. A calm horse should accept this, a nappy horse may refuse to go out again or jog on the way back. When you find something you want to buy arrange your own vetting with a vet you find and be present at the time of the vetting. As above arrive early to check the horse is not being lunged.

Just the thread i was looking for OP :)

We are at the early stages as well, this is great advice.

Being novices would we be better going full livery to start with? I think i have a panic about 1/2 and not getting over 1 afternoon

[away to read all other threads, as this has probably been answered 1000 times :)]

I would assume that anyone walking next to the horse is giving it a lead because they know it may nap. If the horse is suitable for a novice you should be able to take it for a hack alone - that's what you will be doing after you buy it. If a horse and rider are a poor match, which can happen, it should be evident in the arena and there is no point in going for a hack.

I think vetting a are about 250 pounds for 5 stage. They are not a pass or fail sort of thing but rather is the horse suitable for the job you want it for. So a horse may be suitable for hacking and light schooling but not for 4 star eventing. The vetting is also just an opinion on the day there is no guarantee the horse will be fine forever more. Vets won't generally comment of a horse's temperament unless something is really off and they bring it up with you in private. Most horses will have something noted during the vetting, especially older ones. It's no reason to panic, consider the issue in context.