I got the shelving from Menards (they're like a Home Depot, Lowes, or True Value Hardware store). The shelves were very affordable... were less than $15 each I think. Then you have to buy the L-brackets and the wall braces. I think I spent about $60-70 on each wall. It's definitely one of the most affordable, flexible, and easiest ways to display your collection. It really helps out a lot if you're limited on space, which I am.
After I get a house next year with a big basement, I'm going to probably use some shelves like I have now and will also get some bookshelves.
Thanks for the compliments!