I'm kind of in the middle with this one.
I saved some baby stuff from when I had Ben (not just nappies) and bought some new nappies and clothes while ttc (and a few before that
). Then for one reason or another (lack of money mainly, which brought feelings of stress so much it made me stop ttc #2 - long story), and I then had to go through deciding to sell them or not (we then needed some extra cash at that time), and the disapointment of having all these nappies - unsused - and then selling them on. but at the same time a small feeling of relief like I'd taken a pressure of ttc'ing iykwim. I had got them tho (as Rox has said) to help spread the cost (which btw I do think is a good idea).
But personally for me this time round (I'm ttc again from March) I'm going to hold of buying anything until I'm PG. I just found it quite upsetting to have a beautiful stash of stuff - only to have to sell it on without me actually getting to enjoy it, due to a change of plan.
I've been on both sides - not buying anything until after the 12 week scan when PG with Ben, and buying whilst (and before) even having another baby. Good idea in saving money ie spreading the cost, but upsetting if situations change and you have to sell on.