So I have built my PC and everything works perfectly, now all I have to do is put windows on there. Does anyone know where I can find it for a reasonable price below $100 I remember finding 7 for $30 back in 2011 but I can't seem to find 8 anywhere near that. I know it's out there for a steal, and I'm not cheap. I'm just broke after building this PC :P
G2A offers pretty cheap legal codes. Also if your a student, or know a current college or highschool student, copies can often be found for $20 if not free with discounts through your school.
https://teksyndicate.com/forum/buysaletrade/wts-windows-keys-and-few-other-products-paypal-bitcoin/188413
There's also reddit.
http://www.reddit.com/r/microsoftsoftwareswap
You could try that thing that microsoft is doing where you can upgrade from 7/8 to 10 for free. Get a code and download it. Put it on a flash drive, and use it to install it on your new pc. Just spitballin', though. Probably won't work.
Dreamspark.
Use the Windows 10 Tech preview unless you need SLI.