Go do dailies on your main.

But seriously, I gave each of my toons 20g and a full set of bags when I rolled them. I have never bought or sold anything off the AH with them (I do this through a mule) and through questing, silver drops and training, I am at a net loss of about 24g, at lvl37.

If you aren't lucky enough to have a lvl70 main, you may want to take up instance farming. On my very first toon, a (single) warrior (in February '05) I could solo WC at level 40, and make about 10g/hour + AH the greens and cloth. Prior to TBC, farming 10-15g/hour was no easy feat, hence I have not done it since and stuck to dailies which can easily net 150+g/hour