I wish I would have looked more closely at the $4 set when I was in there on Thursday; I would have got a 4-pack. I purchased the Stow Away Utility Box 3-pack for $10, which might be their regular price(?), since it is cheaper than Walmart. I have many Stow Away cases and they're great.
The $10 sets look heftier than the $4 set, but the $4 set ones are pretty good sized boxes for only $1 each. If you compare the middle $10 3-Pack of boxes they're larger than the Stack-On ones from the FP awhile back for $2 each, so it's a comparable deal I think.