I suppose its my turn to contribute something. If you are into Cryptonight mining, which it sounds like a few of you are, check out this Gigabyte mini-pc for $250: https://www.newegg.com/Product/Product.aspx?Item=N82E16856164036
You won't be adding any graphics cards (unless you are using eGPUS) but this thing will hash at 614 H/S. You might be wondering how its possible to get that kind of performance out of a cpu with a 6 mb l3 cache. The game changer is that this processor has an embedded Iris Pro GPU with a 128 MB L4 cache. XMR-Stak recently included an optimization to take advantage of this cache space. It should ROI itself in 2.5 months. You have to provide your own ram and HD, but it does come with a wifi card so you could put this thing anywhere.
Ok, I picked up and set up one of the 5575rs (identical to the 5775, just i5 instead of i7). Out of the box and just using xmr-stak with the energy saver off, I'm getting around 200-202 h/s, which is not great but not bad. I haven't figured out how to enable support for the Iris Pro yet, still working on that, but I'm feeling pretty confident I can get it up significantly...
EDIT: ok, not exactly identical, it's 2.8-3.3ghz and 4mb l3 instead of 3.3-3.8 and 6mb l3, but I still think I can get it up much higher than 200h/s