Im assuming you mean those little play areas you set up, with a movable wire fence. Ive seen them in Wal-mart being sold for 9 something US.
But rather then using that, you should just visit your local hardwear store and buy some mesh, I got a foot of mesh for about $2 so you can get a lot more for cheaper.
Here is a picture of my bin cage. You can see that I used a small piece of mesh for my lid. You can use it on the sides also unless your adamant about having a door in the front you can access the inside of the bin by just taking the lid off.
I had more then enough mesh from the foot I bought to make a mesh lid for Geralds cage too.
Unless you can find or already have a scrap cage I would just by some good quality mesh. Use your best judgment, if its for a dwarf just make sure the mesh linking is smaller then half an inch.