IMO too much of the budget is going into the mobo, it could greatly decrease to increase the psu quality or gpu strength. get a 80-100$ ivy gen mobo, and pair it up with a 7770 or something when it drops in price(which should happen soon, it should hover around 110$) and change the psu.
you choice, essentially, purchasing mobos works by what you need in general its something like:
60-80(barebone mobos for best cost to performance ratio for extreme low end builds), 80-100 (non overclocking mobos with basic functions and a few sata 6gb ports and stuff, great for single card builds), 100-120(basic overclocking boards, generally 16x/4x lanes for crossfirex only. usually a 6 power phase overclocking function). 130-170~(where mobos start to have 8x/8x lanes for Crossfirex/SLI, and an 8 power phase overclocking power system.) any more than that is usually more addons(more usb, built in wifi, more pci-e lanes, thunderbolt port)