Good headphones for 500 on the low?

Hey fellas,I need recommendations for any good heaphones to plug into my machine! what specs should I look for etc...my budget is around 40 bones , so dont plz let me know what r some gud choices!

I use Beyerdynamics DT990 Pro's which cost about £80, but for around the £40 you can get:

(www.dv247.com)
Beyerdynamic DTX 800 - £41.99
Fostex T7 - £39.99

(www.turnkey.co.uk)
Sony MDR-V500DJ - £40.99

(www.soundcontrol.co.uk)
SENNHEISER HD200 £35 (£49.99 @ turnkey)

I know from experience that the Sennheisers are awesome especially in a club, however I find the Beyerdynamics better for studio work.

If you had another £30 to spend you could get a whole different class of headphones and it would make the difference