Can I keep those $1.99 rats they use to feed snakes as a pet?

I feel so sad for them. :/ Also I kicked my roommates out of the dorm so I've been a bit lonely, and I am extremely broke. I have just about $15 to spend. I want to know if I am able to. What things would I need (in the minimum?) I don't need to buy food, I have a lot of rat edible food. Are these rats sick or anything, would I be ok?