Keep in mind that setting up a good Wi-Fi is not an easy task. Wi-Fi (both 2.4 and 5GHz) comes with a lot of challenges, and setting up even a remotely good Wi-Fi will in most areas (at least dense areas) be rather expensive.
It will depend on a variety of factors - but don't go out buying a lot of things before you check these things.
A) What building material are the walls? Concrete is dense and will eat up a signal, wood is not.
B) Are you living in a populated area? Your neighbouring Wi-Fi's will create interference, and if you have a lot, will be a serious issue.
C) Where are you placing your routers/access points? Map good distances, and try to keep them elevated (the higher up, the better).
D) Eliminate own interference. Keep in mind that your microwave oven will actually create rather hefty interference when on - so once again, map your network accordingly.
Best of luck (oh, and as you might've noted, I still think cable is king, heh!)