We have rats guineas and gliders. I made all their cages myself. C&c for the guineas but since the rats can fit through the holes I went to homedepot and got wire shelving, had them cut it to size for me then zip tied it together. They have room to climb, run, and play and it's set up with a fuzz ball pit, stuffed animals, and various climby things. Also those horrible zhu zhu toys....the tunnels make GREAT play things for the rats and gliders both!
I'm a believer in building/making your own cage. So far it's been cheaper by far and bigger than what is available in pre made cages.
I spend tons of time at thrift stores and Jo Ann fabrics to make stuff for all my babies! Oh, and dollar tree.