Actually, I was at a lecture by RMS where he said "if someone wants to pay Eur 30K for your work, by all means, charge them Eur 30K". Often it's not practical

Actually, I was at a lecture by RMS where he said "if someone wants to pay Eur 30K for your work, by all means, charge them Eur 30K". Often it's not practical to charge for the software itself, because people know they can typically download it for free (as in beer) . In that case, you should charge for consulting. (Which is what RMS does)