Do you think I should start my own rattery?

Breeding any animal is a HUGE responsibility. There are already too many unwanted pets. Instead of starting a rattery why don't you start a rat rescue instead? This way you can help homeless ratties, and as an added bonus most of the females you rescue will probably be pregnant anyways so you still get to play with the cute babies! If you breed, even with good intentions, you are only adding to an overpopulation.