To buy something.

Muffet positively beams when you tell her you want to buy something. "Well, that's what we're here for, cutie. What would you like?" She asks. You browse her selection of pastries for a minute, before picking out your favorite kinds of sweets. Once Muffet is done adding them to a box, she places the box on the counter and rings up your total. "Alright, with all those pastries you picked out, your total is going to be 9999G." She says innocently, as if that is a normal amount to be charging just for a few baked goods.

Before you can start to complain, Muffet holds up one of her hands to stop you. "But, since you are quite the cutie, I'll lower the price to a measly 50G. How about it, dearie?" You agree that that is a more reasonable price, and start looking for your wallet in order to pay Muffet. You begin to panic for a moment when you can't find your wallet, only to remember that you never had a wallet to begin with. Muffet starts to frown when she realizes that you don't have any money. "Can't afford it?" she asks. "What a shame, and I was just starting to like you too. Oh well, no money, no service." With that, Muffet takes the box of pastries off the counter and puts them away.

You feel rather disappointed at not getting to enjoy the delicious treats. Muffet must have noticed your somber expression, because she responds with, "Aw, don't be so glum, it's not a good look for you. Tell you what, if you're willing to work for a few hours, I would be more than happy to pay you for your services. 150G sounds very fair, wouldn't you agree? I already have plenty of workers between my spiders and my dear Susie helping me out, so you can pop in whenever you need some extra cash and I'll give you some easy work. What do you say?"

It sounds like a very generous job opportunity, but you get the sense that 150G isn't as fair as she claims. You could try to persuade her into increasing your pay, or you could just simply accept it as is.