Wow! I was wondering the same thing about those grids. They look much nicer than a full grid on the side. The only place I have seen them is on eBay, there is a seller with C&C cages that use them.
I emailed the seller to see if he is willing to say where he got them or is willing to sell just the rounded grids. I know on the C&C page, full grids sell for $1.50 each plus shipping. I am willing to pay that but no higher if he will sell the rounded ones. I will let you know if I get a reply.
The seller is willing to sell them for $1.20 each plus shipping. She has them in red, black and white. If you want her info, email me at [email protected]