I also enjoy my ATH-M50 headphones. They're reliable, fairly neutral sounding and great value at that price point. I highly recommend that if you buy them new, burn them in. Lots of people feel this is unnecessary. I did too, but my headphones sounded thin and tinny new and I really didn't like them at all, but they got alot better and warmer after they'd been played for awhile.
Other than these, I've used Beyer Dynamic DT990 and they are really nice sounding, but the 'pro' version is out now and it's beyond your price range. You can find the DT990 used for 120-150, which is a good price. It's a very bass heavy headphone, so if you're into neutral sounding headphones, there's the DT770 or DT880 models. These all have a very robust cable, so I wouldn't have a problem buying these used (the only in-ears I'd ever buy used would be models with a replaceable cable...since the cables on in-ears never last very long.)
Speaking of buying used, if I was you I'd consider doing so. Alot of people, especially the head-fi crowd, go through headphones like water. You can get a nice discount if you don't mind opening something that's brand new. I like buying headphones used anyway since they've already been burned in.
Finally, if you're just not sure what you want, check out a couple of sites.
www.headphone.com has some top ten lists that is really quite good. Even though headphone.com sells headphones, it seems like their top ten lists aren't biased, say to a particular manufacturer. The other site to check out is
www.head-fi.org, but that site will make your head spin. There are a jillion members and a TON of activity. However, the place to focus is the used gear section, where people are turning over their stuff. Like I said above, these guys are FAN-AT-ITCAL to the f***ing extreme. (In fact, I've found in my dealings that they're mostly a pain in the ass to deal with, their so f***ing anal, but I hate generalizing about groups.) But the up side of the fanaticism is that their used department has good gear, kept in spotless condition, at used prices.
Hope this helps.