well i had mine for a while and I know that they not cheap most the time. I know in Delaware they sold like 15 bucks a piece when you find them , and they sodl under a fancy mice name ( lol makes no since with that name) I have mine in 3 large tansk but I know they were not breeding right and I learned why lol I wasw keeping soemthing like 2-9 ratio cause I didn't have enough water bottles/room to set up about a dozen tanks. I also found if I dumped the rodents into a clea ntub and then wiped the old cage down when I cleaned the males were not getting jumped as bad since it was all a new and clean set up for them.
I also founda chewing trick they liked for a hide/ chew area. I took a small piece of plywood( to fit inthe tank and screwed 4 pieces of 2x3 for legs making a mini table they will climb on hide under and chew on and it made out of scrap wood lol..