Consultants do this all the time, though they don't run specials usually. They negotiate discount for longer engagements and up their rate when they are too much in demand. They grandfather in their good clients and tell clients that are a pain in the a$$ to shape up or ship out (you never want to just cut a client off without telling them why - give them a chance to shape up and a few will become your best clients. Cut the time wasters loose unless you like them, but again, tell them why and give them a last chance). It is all good business, but you have to have good TCB first to be able to pull this off and lots of ladies don't have that yet and probably never will.