there is no question that u should build your own, but before u build u need to have a have a few things down.
1) u need to be able to follow directions, the directions that come with the mother board have to be followed exactly the 1st time u build one
2) even though it will save u money u need to know that if u break something or need tech support u have to go through the parts manufactures, so u need to be sure of ur skills and debuging
3) if u arnt into looking at tech stuff all day u need to go and join a forum and ask for help, i recamend going to
http://www.xtremesystems.com/index.php
or
http://www.therubysquare.com <--- im a mod i will make any1 who asks a parts list for their budget
both of those forums are free and have techie people who will help u pick parts and trouble shoot
4) expect to spend about 10 hours assembling (it only takes 1.5 hours when u get what ur doing) + 5-8 hours of installing software and $1000 on parts and $130 on windows or osx + shipping minimum to get ur computer, but that will last u at least 4 years probably 5 years of gaming