I have three 2002 Audi A6 2.7T 16" Alloy wheels that I don’t need anymore. I was wondering if there would be any used parts stores that would buy my used wheels; it would be preferable for the store to be in the Greater Boston area but anywhere in the Northeast would help.
What about eBay?
I’m from Boston, although not currently looking for any Audi wheels haha 
Best bets are a free ad on Craigslist or post them in an Audi forum. I believe www.vwvortex.com could be of some use to you as they have Audi forums and have quite a few members.
That’s a good point about Craigslist. There might also be a local weekly classified mailer; it’s called Pennysaver in MD. Maybe there is something similar in MA. BTW, Pennysaver does not operate in New England.