I never think someone should decide his budget when buying a computer. You chose your
need and then try to find the best price for it.
If you are searching for a 800$ computer in Canada (which I supose you are since you are talking about canadian dollars), you will find many. Yet, I don't know if they will have so good of graphic cards.
This is a quick find :
http://www.bestbuy.ca/catalog/proddetail.asp?sku_...7&logon=&langid=EN
I don't know if the video card is as good as you wish though..