Difficult to build client base.
Personally I string anyone's racquet as if it's one of my own. Many first racquets I've easily spent 15-30 min cleaning and polishing, 45 min stringing and 15 min polishing up again, applying a new overgrip & bagging. For all of this I might charge $10 plus that of the string. Customer's appreaciate the end result and the economics but some still only want to string their racquets once a year and for ever 2-3 new customers seems like 1-2 drop out of the game.
I'm planning on sticking to this, but it's detinately slow going and far more a hobby than much of anything else.