I have a 3 month old baby and we have spent surprisingly little on baby gear. I suppose it depends on whether or not you want everything new or don't mind secondhand?
The only things you NEED to buy brand new are a car seat and a mattress for the cot / moses basket and that is for safety reasons. Everything else can be picked up easily secondhand / from family or friends etc.
Babies grow so quickly that often secondhand items have barely been used :) We have been given a ridiculous amount of clothes and I don't think we have actually bought anything ourselves (clotheswise) except for a few vests (tbh, we didn't need them as we were given so many but I wanted to buy something after my scan!). Our pram cost £125 and had only been used twice before. It would have cost over £400 new. Our cot was £300 but is a cot bed and was a present from my parents.
We did buy a baby bath (£3 from Morrisons) but up until now have just washed baby in a washing up bowl as it is easier than carrying the bath! We were given a moses basket and bought a new mattress for it (£10) but I know lots of people don't bother with moses baskets so it is up to you :)
Travel cot (we travel a lot as our family live 70 miles away) was £40, reduced from £80 and can also double up as a playpen when baby is older (not sure if we will do that with it, but it says on the packaging that you can do that with it).
Muslins - we use a lot of these. You can get them very cheaply at Tesco / Asda / John Lewis although we were given most of ours.
Baby gyms - we were given 3 different types by members of the family but you can pick them up very cheaply in the classifieds of your local newspaper (in fact that goes for any baby equipment!)
Clothes - we were given loads of little outfits but most of the time ds is in babygros (up until now at least) as they are comfier for him and easy to change when he is sick / wees all over himself etc. He has some outfits he has never worn and are now too small for him 
Nappies - we like Aldi and Asda nappies. We didn't get on with Huggies at all and although Pampers were good, they were on a par with the Asda ones which are half the price...
Sorry for rambling on! It's a very exciting time getting ready for a new baby - enjoy it :)