So I saw this idea on another blog.. and eek! For the life of me I can't remember which one (I'm only 23, this is not a good sign). So, if you recently posted about this tell me and I'll credit you!!
I went to Home Depot today and brought my crate in so the man could measure for the wood, two pieces turned out to only be about $6! My crates are form Target and they were about $5 each.
Then I went to JoAnn Fabrics and found the exact fabric I was looking for :) I bought 2 yards, which was plenty!! I also printed off this coupon which helped.
I found these foam squares at JoAnn's as well; and some Elmer's Spray Adhesive (only a small 4 oz can for $4.95)
I'm lucky to have a handy dad, he cut the foam for me with an exact-o knife and I spray glued it on. Then I lined up my fabric and pulled it tight while he staple gunned it on! This whole process took only about 25 mins :)