Most people do not mind waiting for a few months until the book they are looking for has a discount or they are able to get a good bargain on it. Unless you are an avid book fan of course, you should be able to get a reasonable price on the book of your choice by being patient for just a while.
Most bookshops have their own annual book sale. At this sale, you should be able to find the book of your choice at a good bargain price. I know of some sales where books can be up to 70% discounted and they are snapped up in no time. Therefore, be sure to get there early or else, the worm gets caught by the early birds!
Finding bargain books should also not be a problem over the net. Auction sites or online bookstores usually stock up books or have book for sale at very low prices shortly after these books are in the market. I don't think it will be much of a hassle trying to find these books as I myself can find it in no time!