I'm not an expert by any means dude but I just had a look around so I could reply, mainly to put your thread back on top as mine is old.
First thing, does it matter to you what processor you're using? If you can find SB on the cheap, or you don't mind just getting one SB and swapping out the chip to BIOS updates if ncessary, then you could get a bunch of SB h61 boards. Those are all pretty cheap. I'm seeing a bunch on pcpartpicker.
There's this http://www.amazon.com/dp/B00CP87B20/
and it's gigabyte so I don't think it would be a problem.
and then there's also thishttp://www.newegg.com/Product/Product.a ... 6813157315http://www.amazon.com/dp/B002MRROO4/
those old h61 Asrock's don't have the best audio sometimes. So you could also get thishttp://www.amazon.com/dp/B008VFL6L8/
edit: After another look, I've decided to mention this http://www.newegg.com/Product/Product.a ... 6813128589
with that you get less pcie lanes than GA-H61M-S1 but you get usb3 via a via (haha!) controller and you also get a dvi port on the motherboard. a quick look on the gigabyte site shows the usb3 to bear the "ultra durable" badge or whatever so that one might have better capacitors and transistors, chokes and other things and whatnot.
However, if you need a newer chipset, then you could get one each of thesehttp://www.newegg.com/Product/Product.a ... 6813128667http://www.newegg.com/Product/Product.a ... 6813132052
and make the rest of it up with thishttp://www.newegg.com/Product/Product.a ... 6813130731
I would think you'd be better off getting haswell or ivy bridge board (but no haswell chip) because the SBs are becoming rare, their repuation (irrelevant on lower end chips but well whatever) is driving all of their prices up, and some of the boards of that era lack nicer features found on modern boards I think. so yeah.
I don't like MSI though. On the lower end of their stuff they aren't the greatest. Should be fine on a nice low tdp but I dunno.
I have no experience with any of this. like I said I mainly just replied to you put your thread back as the first. This is also just what I got from a look with pcpartpicker. hope you get some good stuff.
edit: and are you sure about $50? if you go up by $10 you can get in range of basic haswell gigabyte and asus boards not on sale.
There's no motherboard reviews and there's just no motherboard reviews at all for lower-end motherboards. You would think that manufacturers would send this stuff out to reviewers to put into a big low end roundup or something. anyway this is just what I could find fairly quickly. hope you get some nice stuff dude