This is $255 , a little over your budget and can handle gaming on dual monitors at good settings , for 3 monitors you really need much more ( CFX or SLI is more suited ) :
PCPartPicker part list:
http://pcpartpicker.com/p/WzJMFT
Price breakdown by merchant: http://pcpartpicker.com/p/WzJMFT/by_merchant/
Video Card: Gigabyte Radeon R9 290 4GB WINDFORCE Video Card ($255.00 @ Newegg)
Total: $255.00
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2014-10-20 15:11 EDT-0400