Ok, general question for you all...

At what point would you consider it a good idea to start breeding your own feeder rats? I'm sure I'm not there yet, I've only got 2 BP's who cost me a total of about $3 a week in rats, and I'm sure raising my own would be more expensive than that. At what point though, would you say the cost/benefit of switching to raising my own becomes attractive enough that it's more or less a necessity?