I have Sony 7506/V6's and I like them a lot, but they can be a bit fatiguing, both for fit and for being a little harsh sounding. They have great big bass though and area lot of fun and very clear. I wasn't a fan of the ATH-M50's when I heard them but lots of people like them. Beyerdynamic's simply don't fit my head, they are too small for me. In your price range it is worth checking out the Grado line (SR-60/80/125), some people love these, I'm not one of them but you could be. Sennheiser makes the HD280s around this price, also worth checking out as well as the HD-25's which are really nice but a little pricey. I use AKG K701's at home and I like them a lot for clarity and accuracy (which I really appreciate) but they aren't tons of "fun" and I usually listen to music on speakers.
Try to listen to as many different cans as you can before buying and don't be fooled by big boomy bass or overemphasized treble, listen for clarity and accuracy as well as a sound signature that you find pleasing. Visit your local shops and bring your own MP3 player or CD's. Check out head-fi.org for more extensive discussion and maybe even a local meetup if you are really into it.