Getting A Chin?

So I was in the pet store yesterday and they were selling 2 chins (separately). I was sticking my fingers in the cages (at this point I had no real thoughts about actually getting one) and one of them seemed to react like it didn't care but still let me pet it. The other one was literally pressing itself against the cage and didn't leave my side unlike the other one. Is there any way to guess how the loving one will act if I buy it. I mean I adopted a dog once and he played fetch at the pound. Once we got him home his does not play at all. So I don't want to pay over $200 for a chin just for it to change and act differently.

Chin's are not a pet you should buy on impulse. You need to do a boatload of research beforehand, and you shouldn't really buy a chinchilla (or any pet for that matter) from a pet store.
Chinchillas require a lot of attention, a lot of toys, a lot of cleaning, etc.
Also they have very strong and varied personalities, Chinchillas are very smart. There's no way to predict how one will act without long term observation.

It takes a certain kind of person to care for a Chinchilla, it takes a lot of time and devotion. I don't mean to be rude, but you should put a whole lot of consideration into this before you go through with it.