Nazly I tried loads of makes of nappies and found Pampers to be the best for us, fit well and didn't leak. The supermarkets often have really good deals on them too. I could have cried when I realised they didn't do them here (NZ), nappies here are pretty rubbish and expensive. Luckily we shipped a massive load out in our container for DS2 when we moved, but won't be able to do that for DC4 
There always seems to be deals about for pushchairs etc, you don't need to necessarily wait for sales. I always found Sainsburys clothes to be really good (I'll be reusing a few of mine again for the 4th time so they last!) and they used to do 25% off sales quite often (haven't been in the UK for 2 1/2 years though so I'm not too up to date :) It wasn't until I left the UK that I realised how cheap clothes are there - my mum is bringing me some out with her :)
For second hand sales, look out for NCT sales, we got lots of stuff through them. The only thing you have to watch out for is that if you help out at the sales you get first dibs on all the stuff so a lot of the good stuff has gone before they open the doors to the general public. I helped out at a couple and got some brilliant stuff really cheaply - I can't remember if you have to be a NCT member though for this (I was due to attending the antenatal courses).
Have a look out for Mountain Buggies on Ebay, they are bombproof and you can get carrycots etc for them.
Good luck with your scan Nazly, I've got mine next week too.
Also, I purposefully don't own a set of scales, I live in blissful ignorance 