If you get this far...
My DS arrived 2 months early with no warning whatsoever, so my top tip is anything you really think you'll need - GET IT NOW!!!!
Seriously, it proved to me you don't need much, not that I ever thought you did. I was lucky in that both my sisters had kids first, so I got given a moses basket, baby bath, blankets, sheets, clothes, breast pump, bottles, all of which you may need - I'd definitely recommend a moses basket unless you plan to co-sleep for months, as when DS came home from hospital after five weeks, I carried him from room to room for ages cos he was so wee, didn't feel comfortable leaving him in a room alone. He stayed in it next to my bed at night until he was nearly eight months (six months adjusted) old and his head was inches from the top! I didn't want to move him into his own room until then, no room in the bedroom for a cotbed.
We also got given a cotbed from friends, and could have had one from my sister too. If you don't have people around like this, an invaluable source of free stuff is freecycle.co.uk (or .com, not sure). It's a recycling service, and you can request things as well as search for them.
DON'T bother buying clothes apart from a few bodies and babygros - unless you are a complete hermit and know no-one, you will get given more clothes than your baby will be able to wear for the first three months, maybe longer! And as other posters have said, there is no point trying to force a tiny baby into proper clothes, which are almost always stitched too tightly in inconvenient places anyway, particularly if you have a clothes change-hating baby like mine . Babygros are the only thing you need in the beginning.
Sling was invaluable cos I didn't get a pram for three months or longer, preferred carrying him anyway. I have to confess I did buy an expensive pram/pushchair, or rather DP's dad did, but it was what I wanted and would have paid for it myself anyway if necessary cos I love it for numerous reasons (Bugaboo Cameleon) - you have to decide what is important to you. That's the only thing that cost lots of money. I also found a changing table useful because it hurt my back changing him on a normal size table or the floor. Got a basic but perfectly useful one from Ikea for £15.
If you join Boots parenting club (free) and buy a pack of Huggies, you get a free changing bag with mat.
Once he was bigger, used a sleeping bag for him. Asda sometimes sell them for £10, and a cheaper and better alternative to Grobags is the Dreambag at thedreambag.com
Waste of time:
Bottle warmer
Top and tail bowl - used two plastic Christmas pudding bowls we had in the house.
Was given but have never used nappy bin - just bag them (or use reuseables if you're more organised than me!) and put them out with the rubbish.
Baby towel - stupid shape and not big enough - a normal towel is fine.
Wow, long post, sorry for running on...