What is this customer buying for his house?

A customer walks into a hardware store looking for these things, of which every house should have at least one. He finds them hanging in a display rack, but cannot find any prices. So, he takes two off the rack and walks to the front of the store to look for the shopkeeper. When he finds her they have a conversation, which makes perfect sense and goes like this:

"How much are these?" the customer asks.

"They are a quarter each." says the shopkeeper.

"That means seventy five cents for 100?" asks the customer.

"Yes, that's right." the shopkeeper says.

"OK, I'll take 73 please." says the customer.

"Very good." the shopkeeper says, "That will be fifty cents plus tax."

Can you figure out what this customer just bought?

Are you sure you want help with this brain teaser?

Sometimes, answers to difficult problems will come to you when you are thinking about something else. And, solving a problem on your own can be very rewarding. B4U look at the hint, you may want to read the puzzle again, very carefully, and give yourself a little more time to think about what the people in the puzzle are really saying. Identify the facts that are important and forget about the ones that are not. You can do it!