Actually 2 male rats that have never met each other before can be introduced... slowly. It just takes time, and patience.

If I was you, since you want a male, I would just get 2 males from the same place, it will be a lot easier that way if you get a pair that has already been living together.

Like DJ said, spay and neuter surgery is very expensive. However, getting a female rat spayed reduces the chance of tumors they will get when they get older.

Here are 2 great rat forums that you might want to join and ask more questions on. I am a member of both, and everyone is always very helpful.

www.goosemoose.com/rfc
&
www.ratpalace.com