DH & I pretty much stocked up major items at around 20 weeks, after our last u/s and once we knew bubs was ok (low downs syndrome risk, all limbs there etc...)
I've gradually stocked up on nappies, washing powder, nappy san, breast pads, maternity pads etc.... when I do our weekly shopping and if/when those items are on special.
I suggest having a look at some 2nd hand / preloved baby shops and places like the Salvation Army etc... You can get some really good 2nd hand baby clothes from the Salvation Army and the likes. Make sure that if you are buying stuff from those places that it meets Australian Standards. Also, do you have any friends that you can borrow things off? I am borrowing a craddle from a friend, a bouncer, nappy bag and I have been given a whole heap of cloth nappies and bunny rugs as well as 4 0000 body suits for use in hospital. You could also hint to a friend or relative about them giving you a baby shower..... (you might be uncomfortable with this??) I can't suggest Ebay as I've never bought stuff off there, but some of the other gals would give you some pointers about that.