That's exactly what I pay where I go to school. Try not to listen to the people who tell you that you're grossly overpaying, because depending on your relative geographical location, you'll pay a hell of a lot more or less than average. I used to live in Boise where quarters ran me $100 but over here in Eastern Washington they cost me $70.
Ultimately, weed prices are entirely relative. Trying to compare prices between cities is almost apples and oranges. What I would suggest is trying to find an alternate source, someone your dealer doesn't even know. See what he charges you, and if it's better, then stick with that guy.
Wash. Rinse. And repeat until you don't think you could do any better. In the end, you'll have multiple hookups that will protect you in case of a dry-spell.
Happy Toking.