wilkinsons have some good priced mesh that princess-rhi is always suggesting (hopefully she can post a link for you)
But it can be found in all sorts of stores, personally i got it from a local pet shop.
Just be sure to make sure its not too sharp or thin so the hamster could chew through it!
My cabinet cage homes a russian dwarf, it measures 36 x 53 cm approximately on each level (so 72 x 106cm overall
)
But it doesn't take up too much space and it snice that it looks like a normal piece of furniture with storage space too!