[Etherate]

  You can find plenty of decent amp for under $100 + AD900X would still be cheaper than the Beyer DT880.

 
What would i connect the $100 amp to? onboard pc sound? or receiver? thought i would need a DAC too... which is more $$
 
I can get AD900's for ~$200 and DT880s for ~$250, so its still in my budget.
 
if i wanted to get a different source for the headphones i need to spend another ~$200 (e.g. Schiit Modi+Magni or Asus Xonar STX)
 
In any case i still need a receiver to run my speakers and sub. So for now i might get the DT880s because i assume it would be less of problem than the AD900s off the receiver. And ill look at separate DAC/AMP combo a bit later down the track.

 

[kookoo]

Apologies, I thought the AD900 were cheaper than that. In which case grab the DT880 ( i assume you have listened to them first and enjoy the sound signature) and think of upgrading other components later.
 
I believe Fiio has some amp/dac which are good value for money, or as you said save up abit more for something  better

 

[PurpleAngel]

  Ok I'm now thinking I'll get DT880 Pro's 250-Ohm... that should be alright?

Going with the DT880 for now means you really do not have to spend cash for anything else.
In the future if you decided on different headphones the DT880 is an easy sell.
DT880 $212
http://www.bhphotovideo.com/bnh/controller/home?O=&sku=567894&is=REG&Q=&A=details
 
I've had the itch for buying the AD900X for months, even thou I really have no need for it.
But if you bought the AD900X, you would want a low impedance amplifier like the Magni, $99 and a decent DAC, like the Asus Xonar DX or D1 sound card (CS4398 DAC chip), used $60.