Where are your from Op? We can't give you any real advice if we have no idea where are you from, there are big internet shops located in the US like Overstock, Newegg, Dell and in the UK: Aria.
You can use plenty of 'less' official sites to buy stuff from - Shopawl.com - they can get you anything from banggood or aliexpress. You can get Amazon gift cards from gyft.com... and so on...
With Bitcons you will be able to build any PC you would like without even need of exchanging BTC to 'money'. Just google for bitcoin accepting shops in your region.
Few posts later he wrote he is from Korea. I googled for a few seconds and immediately found some eshops which are accepting bitcoin. I found also a korean service which pays for you at some big shops which don't accept bitcoins directly.