If you play out at all you need something to sell at gigs and people tend to take you more seriously if you have a CD. For promotion we have given away as many as we have sold. I think if you break even on a CD project you should consider yourself successful.
As someone on the jugbandz mailing list said: "It's a million seller -- I've got a million in my cellar." I think if I were going to do it again I would put the money into duplicating equipment and produce only what I need at a given time.