All the accusations thrown against you are total bollocks, I've been a long time seller myself and it costs me close to nothing to keep my refund guarantee, and it wouldn't cost OP much either. Most of the time when it's in regards to refunds, it's mostly human error as you sometimes need very specific ISO files and such, or activate the key before installing service packs and such.
Thanks for supporting me. I appreciate it big time mate.
I don't know why people are so butthurt about this. I just bought a Windows 8.1 key and it worked flawlessly!
Personally I don't care if it stops working after a year or what not, for 5 bucks I have genuine install of windows with no crappy KMS service or any kind of malware dumped into it like the popular torrented ISOs.
I recommended your website to my friends so they can get off crappy pirated versions and finally have a real version of office, etc. Keep it up!