The main focus is whether or not you are overclocking. In true reality, you can get a $70 motherboard and get the same quality of performance as a $250 motherboard (assuming you don't overclock on either board) since the components on the board are what do the work (I am not saying there is no difference, better motherboards have better chipsets and support higher RAM speeds). The main difference in the cheaper and more expensive boards are that they will have more memory slots, more PCI, PCIe, and PCIex16 slots, more SATA ports, and pretty much more available options that very often go unused. But the largest factor for getting a more expensive "Z" board is to overclock the CPU.
If you are not overclocking, Any $70 will work perfectly fine. If you are overclocking, there are a variety of options. There is the MSI Z97 Gaming board for a cheap $130, or if you want to achieve a higher overclock the Asus Maximus VII Hero is great. And there are tons of other options by other and those same manufacturers. You should scam around pcpartpicker for any that interest you.