Also, a GREAT way to listen to a lot of awesome headphones, and ultra-expensive headphone equipment setups is by looking for the meetups on head-fi.org
Very friendly people and a whole lot of people that love audio. You'll come back home with a whole list of music suggestions and a plenty of new headphone knowledge
I'll second that. We're a great group here, but our collective knowledge of headphones might not be as deep as the OP would like. The folks over at head-fi, well, they're on a whole different level when it comes to headphones and their accessories.
If there's one site to visit to learn about headphones, it's head-fi.
And buying used can save you money, no question. But I don't know if I would want used headphones. It would depend on the savings. Being worn, headphones are kind of personal. And especially IEM's. I don't think I'd be comfortable with using someone's used IEM's.
If you go the used route, you may want to pick up some replacement parts to freshen them up a bit. You'd definitely want fresh & new tips if you get IEM's. And with normal headphones, you may want new/fresh pads. Neither are very expensive. Just something to think about.