I think with this amount of money you can have a good one. That´s something, respect. 
Thank's :-) but i don't really know which card i want to buy because:
- I can buy aprox. 3 card's 350W each
- or buy ~4-5 card's 250W each.
What is the best choice? Of course when i'll buy i want to overlock and configure this :-)
I'd go for 3x 350W, since You will need 1 PSU only for that(and 1000W and more are much more expensive) + You have more mobo options.