If you decide to go with the APU + Xfire GPU combo (which I think will be potent enough), here is a potential build, including three 24" displays.
PCPartPicker part list /
Price breakdown by merchant /
Benchmarks CPU: AMD A10-5800K 3.8GHz Quad-Core Processor ($119.99 @ Newegg Canada)
Motherboard: MSI FM2-A55M-E33 Micro ATX FM2 Motherboard ($46.99 @ Newegg Canada)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1866 Memory ($49.99 @ Canada Computers)
Storage: Samsung 840 Series 250GB 2.5" Solid State Disk ($169.99 @ Newegg Canada)
Video Card: Asus Radeon HD 6670 1GB Video Card ($82.04 @ DirectCanada)
Case: Corsair 200R ATX Mid Tower Case ($49.99 @ Canada Computers)
Power Supply: Antec EarthWatts Green 430W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply ($59.99 @ Memory Express)
Optical Drive: Samsung SH-222BB/BEBE DVD/CD Writer ($19.99 @ Memory Express)
Operating System: Microsoft Windows 8 Full (64-bit) ($109.99 @ Newegg Canada)
Monitor: Samsung LS24A650SS/ZA 60Hz 24.0" Monitor ($219.99 @ Memory Express)
Monitor: Samsung LS24A650SS/ZA 60Hz 24.0" Monitor ($219.99 @ Memory Express)
Monitor: Samsung LS24A650SS/ZA 60Hz 24.0" Monitor ($219.99 @ Memory Express)
Total: $1368.93
(Prices include shipping, taxes, and discounts when available.) (Generated by PCPartPicker 2013-02-26 16:07 EST-0500)