Hmm, I kind of understand what this thread is about, but I'm not sure you should use the word "Extortion". Extortion is getting money from somebody by use of a threat, like bodily harm or public humiliation. I think what you really mean to say is "overcharging". Some other words you could use to describe the phenomenon of which you are complaining: fleece, gazump, cozen, diddle, rook, plume, rob, defraud, soak, hook, pluck, cheat, rip off, chisel, con, skin, stiff, sting, swindle, stitch up, take for a ride, and take advantage of.
