I go to a shop I pay $350 and I know roughly what the outcome will be.
I ask the WL if I can finish her off with a facial, she hesitates and suggests that I can give her a pearl necklace instead, not happy with this outcome I ask her if I can CIM instead to which she agrees, that is called negotiation (the price is fixed and money is not discussed). If she was to ask me to pay an additional $50 for a facial and I suggest $25 instead, and she agrees....that is haggling.
If I was to pay her $250 upfront and she gave me the works including MSOG, facial, pearl necklace, CIM, bareback and anal then that's a bargain.if I get an STI as a result of the encounter then that is TOFTT.
if another punter pays the same $250 amount expecting the works but only gets a cbj then that Is YMMV.