I currently use a $20 pair of Sony headphones purchased from Sam's Club roughly 11 years ago. I had purchased a pair of $14 Memorex headphones from Walgreen's but those didn't last more than a month of regular use so I went back to using the Sony's.
I don't currently use a headset. I use speakers and a stand mic. I have, so far, been unable to find a comfortable, good sounding headset for a reasonable price. (Sure, the Bose headsets are comfortable, but I'm not going to spend $600 on a headset without a mic.)
I use my sennheiser headphones for my audio. I bought them to use with my ipod, so every time I want to go out I have to crawl under my desk and unplug my headphones. Now with these I would have a dedicated set for my computer.
I use a Plantronics .Audio 355 headset. They sound pretty good for stereo headphones, but I have to readjust them about every 20 minutes because they feel like they're pinching different parts of my ears.