I recommended a few headphones for someone else on here a few weeks ago, so I'll just repost it as you have the same requirements he did. $50 range, headphones not buds. The poster went with the Panasonic phones, for your reference.
http://www.amazon.com/gp/product/B000IBRX4M
I bought this pair for my friend and she loves them. She'd been using stock iPod earbuds before this and when she switched to these headphones, it was so different that the new pair gave her a headache. These were that good for her. Granted, it'll be a different experience depending on your ears, so grain of salt and whatnot.
http://www.amazon.com/Koss-PortaPro...1?ie=UTF8&s=electronics&qid=1204616690&sr=1-1
The Koss phones might be a bit ugly, but they aren't slouches in the auditory department. They're backed by lifetime warranties and are affordable. Good phones, good quality and a good price.
http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=02RGMMV3R9P2CW70KS3D
Then we have the Sennheiser 202s, they're affordable and good sounding as well. They're pretty durable and are closed headphones, so they'll do a good job at keeping noise out.
But for just a little more, why not get a higher quality headphone, no? I present to you the Sennheiser HD-280s.
http://www.amazon.com/Sennheiser-HD..._m=ATVPDKIKX0DER&pf_rd_r=0C61SQ6YWJEQVES2TBWE
http://www.musiciansfriend.com/prod...hones?sku=241473&CJAID=10383227&CJPID=1225267
Also, the Sennheiser HD515s are available here for $59 after discount. They're a nice set, and you're getting a great deal as they're typically $100.
So far, these are the ones I can think of off the top of my head within your budget. I'll post again if I can think of any more.
Sorry if I went a little overboard. I get unnaturally excited whenever anyone is in need of headphone shopping. I've owned most of these pairs with the exception of the 202s. My first pairs were the Sony MDR-500s, then the MDR-700s. I was fine until I listened to a friend's Sennheiser HD-580. Then it was over. I'm currently using the Beyerdynamic DT-880 Pros and am in love..they're a bit pricier but just so comfortable and so great sounding.
Anyway, I'm going on a tangent. Sorry.