ill note that the reason why this is extremely hard to fit in a budget, is because of the fact that unless your gpu is a single slot gpu, it WILL cover one of the other PCI lanes, in which at your budget, almost all the choices are Micro ATX, and you want to use all 4 PCI lanes.
strict budget wise, one of the earliest non micro atx mobo that I know would fit the need is an asrock z68 pro3
pcie 3.0 is backwards for all older video cards. to get pci 3.0 you have to have the correct chipset and cpu and a pci 3.0 video card. people with the older sb cpu if they toss in a 3.0 gpu it run at 2.0 speed. to save you a slot on your mb have you thought about using a usb wifi stick??
no tom with today mb the pci 3.0 is a new standard. it not on all mb and cpu yet. only the newer chipset and some of the newer cpu have it. if you dont have the right cpu or chipset the mb and video cards will drop back to the older pci 2.0 bus speed. also right now there no video cards that can max out the pci 2.0 bus yet. maby the 8000/700 line of cards can but not any card on the market today.