When I stated to answer your post, I did just a little bit of google research and found that lots of things had changed (especially with the local business where I bought my blocks) in just the last few years since I built a pretty decent sized retaining wall. I can't tell you where the cheapest or best deal will be, but I can tell you that I found it important to evaluate the product first and then look at the price. The durability and aesthetics of your wall can be significantly effected by which product you choose. Instead of just shopping for price, I'd go to some local suppliers and see what they had to offer and how their product compared to that of others. Larger suppliers are going to have competitive prices (or they wouldn't be in business), so compare product first and then look at price.