Best sub $25 headphones

As far as general recommendations, the monoprice 8323 and the koss ksc75 will fit in your price range.  I personally didn't like the 8323, but its been awhile since I've tried it so I can't really remember what displeased me about it.  I myself am a big fan of the ksc75 assuming you don't mind an ear-clip design.  Its a strong performer as far as rock goes, not really experienced with it with other genres.  It is open, so if you are at all concerned about bothering those around you, it won't be that good of an option.

I'm sure there are other headphones in this price range that'd also be worth considering, but I can't think of any others off the top of my head.

The JVC S400 is close to that price and gets good reviews as well.

Panasonic htf600

I personally don't feel it has this problem, but that kind of issue is very subjective.  Hopefully a few others can chime in and you can see if its worth giving it a try.  Also if you're planning to buy from Amazon, they have a very good return policy if you get it and decide you don't like it.

Incase Pivot.

I promise you.

They are completely under the radar right now. They blow away all other <$70 headphones I've heard.

I agree with the Panasonic HT600 recommendation - and I am a Sennheiser fan.  I have the 201's - but rarely use them.  When I do, it is just to sleep in, really.  I think I paid about $11.00 for a refurbished pair about 6 years ago.  I got a pair of HT600's for $18 recently, and I love them.  They do take a while to settle in - but when they do - they are wonderful.  To me, they sound almost similar to my PX 100s, not as crisp, but nice.   They are a very relaxing - mellow sounding headphone - 

Another headphone that a lot of people over at anythingbutipod like are called Cortex CHP 2500.  I have those too, but have not really tried them, and I am sending them back because they came in white.  For the few minutes I listened to them before packing them up, i found them to be a bit muddy - but I felt the same way about the 600s at first. Maybe they need a little burn in too.
 

But my vote is for the HT600s, especially for a comp or home stereo.  There is a very long thread here about them.

If you're on a tight budget, you could also go with used, refurbished, or open box. The sales forums here and the deals thread are good places to look.

portapros or monoprice8323's

accept no others.

Portapros aren't always the easiest to find at $25 or less tho

Unless you don't like open headphones, I'd go for a KSC75 at that price. If you don't like earclips, you can always pick up one of those cheapo Parts Express headphones and use its headband (and throw away the Parts Express drivers, trust me on this one  ). If you can pick up a PortaPro at that price, that would be good too, and certainly better-looking, but I think the cheaper KSC75 actually sounds a bit better.