Today my friend and I found a rat at his dorm. It had obviously been someone's pet, since it wasn't afraid of us and allowed us to pick it up without much fuss. We asked around for quite a while, trying to figure out who the rat belonged to, with no success. We weren't sure what to do with it, and his roommate's girlfriend was horrified by it, so I took it home with me. He seems pretty healthy, I looked him over as suggested by some sites for choosing a rat and he's breathing normally, no discharges anywhere, his fur and skin looks normal. I would like to keep him, so I've been doing some reading on rat care. One thing I can't find are any estimations on the cost of keeping a rat. I know vet bills will be expensive, but how much should I be expecting to spend weekly/monthly? I was talking to a friend who used to have rats, and in the cage he just used old towels and not any kind of litter or wood shavings. Is that okay to do? Also, since I expect I'll probably end up with a second rat in the near future to keep him company, is it much different to care for two rats as it is for one? Would it be okay for a little while to keep him in a smaller cage than recommended if he doesn't have to spend much time in it? If anyone could help me with those questions, I'd really appreciate it!