PS:

I'd probably have degu instead, as they usually live longer, and I was wanting buddies to go to University with :3

ive never had rats, but i had mice.

i recommend keeping females, they dont stink as bad and they dont fight as often.

I think it'd be a pretty cool idea. Pets make really great company. Never raised rats/mice, though.

I currently keep a cat at my apartment and having him there really helps when I get lonely. Food / litter isn't a whole lot extra in terms of cash, so I think it's definitely worth it.
Also, I have a left over terrarium that I used to keep a leopard gecko in when I first moved here, and I was wondering if anyone thought it'd be a good idea for me to try raising a ball python in it. My father has one he's been trying to give away, and I have raised one before. The only problem is that I'm not sure how Frito (the cat) would react. He didn't really mind the gecko too much.

If I could tame, provide a decent food supply, and provide a good living environment for any animal, it'd be this guy. Komodo Dragon.