I have always subscribed to the idea that overclocking is avoidable and not necessary under normal circumstances. By all means if you are an enthusiast and love tinkering all the time, go for it. If you want something to just plug in and work and last the life of the product, just get something that works for you in stock format and run with it. The bump in performance is usually not worth the life you take off the product, at least to me it isn't. And frankly an i5, particularly the last 3 generations of it, are more than fast enough for just about anything you can throw at it.
The difference between a $200 motherboard and a $70 motherboard is usually A) number of pci-e 16/8x slots for SLI, B) number of high performance sata/usb headers, C) overclocking controls, and D) better heat pipes/sinks to cool all the extra crap. Since SLI won't do anything for you, and you probably won't be running 4 Sata 6gbit/s drives, and overclocking for mame is kind of overkill, there is no need to get some crazy cutting edge motherboard. Extra USB headers is nice to have but they don't need to be USB3.0, and most mobos, even cheap ones will have 4 headers (2 ports each) which is more than enough for most cabinets.
A Gen4 corei5 with a basic motherboard, 4-8gb ram, an ssd, and a moderate GPU like a 740 will get you way under that budget and run it all without a hiccup. If you really want to blow more money, bump the card up to a 750ti or 760, get a bigger SSD, a bigger PSU, and maybe bump the CPU up to the top i5. The last 2 gaming rigs I built were right at $1000 usd and while not bleeding edge by any means, perfectly competent gaming computers that could play anything on the market at 1080 with some decent options turned on. An extra $500 gets you 5-10% more overall performance over what it could do, and an extra $1000 on top of that will get you another 5%. After that you might get another 3% overall but it will push you into the $5k range to get it. The returns just aren't worth it to me. Your money though.