I agree with the, ever wise, (sincerely)John Nephew completely. We started relatively small (3000 or so units) and were just kicking off. We are not hurting at all becuase we actually are growing so that we are in the ranges of what Hard8 demonstrated.
Our biz model for modules is exactly what John said. Make enough to be out of them in six month and be done with it.
Larger guys were able to do 10-30k print runs last year and could not even touch that this year. So, as stated, hurting is a matter of perscpective. Still, d20 products are selling just fine if you are modest in your approach and still do better than many non-d20 RPGs in terms of sales.
Starting new though, ouch, if I tried to start now and did the math I would throw in the towel before launch. The numbers aren't in the cards for a new d20 publisher to launch now. It would be a precarious and rocky road at best. This is regardless of how good the material is. How many more publishers of d20 need to be around when there is plenty "right now"!
Now, I say that, but I just saw a brand new company with a brand new module at my game store. So, it is not impossible to get launched but ya better be ready for a slow start and longer period before collecting.