One other thing to consider....
For most folks here, they are building a huge box to fully house controls and a monitor. To some degree, authenticity matters. The controls seems like a terrible area to skimp. You might be able to "get by" with not perfect controls, but why would you do that to the end experience?
Everyone finds where they are willing to sacrifice some authenticity. Using a LCD instead of a CRT, monitor orientation, mame vs original hardware, etc. Controls is an area where many don't want to sacrifice too much. Try a balltop with a diamond shape restriction and if you're a product of the golden era of video games, I think you'll find it feels familiar.