I think, considering what else is out there, $40 is stretching their value, $30 isn't a bad deal and is about as cheap as you'll get them. They're quite a lot bassier than the er6 but you'll be forever wondering whether you can take that piece of cotton wool out that's clouding the details.
If you're comfortable taking your headphones apart for a moment, I'd go for the lower end (and considerably cheaper) HD555s and perform the foam mod on them, which involves removing the driver cups to get to the grilles beneath and removing the strip of foam that is placed there. After that mod is performed, the HD555s are nearly identical sound wise to the 595s.
Trust me, I've done it and it sounds a lot more complicated than it actually is. In reality, you're talking five, maybe ten minutes worth of really easy work here.