Wraithan

Well I think the replacement in django's tests wouldn't be for general unit tests but instead to replace their tests client that one can use to test your own views.

Raise your rates. It is simple. If you provide a higher quality service then you will continue to do well. As you said you are turning away potential clients at this point. That means you have very little to lose by raising your rates a bit. You are already losing business, might as well turn a better profit while you do it.