You really should build your own PC. Store owners ( this includes website) charge so much more just to put all the parts together, you can save hundreds of dollars for the same build by building it yourself (allienware is a good exemple, you pay for the brand more than the product) Don't get me wrong, the PCs are good, but you are still overpaying because of the brand.
Make sure you buy a CPU that can handle your graphic card( getting a super expensive graphic card with a cheap CPU wont do you any good since your CPU is going to be holding you back from the performance your graphic card can give)
Also, most important thing is to get a SSD, install your operating system on it (which you will have to buy, so include that in your budget) and maybe a few of your favorite games ( SSD are smaller or ridiculously expensive if you want a big one) install everything else on a separate hard drive.
I suggest you use pcpartpicker (there is a version for US and a version for Canada). If you are not comfortable picking your own parts, browse the pre-made builds or the forums and you are bound to find something that fits your budget. This website will also allow you to see what site offer the best discount/price for every part you pick, making it really easy for you. Try to stay away from mail-in rebate as they can be a pain in the ass some times.
Don't be afraid of building your own PC its not as hard as it looks, read a few guides, watch a few videos and you should be able to handle it.