Do they have pre-build cheap gaming pc's,

They have just about anything you want. Prices are very reasonable, in the last week I bought 2 laptops and a tablet for about $800.

Yes pretty good ones too we got one for my wife for 300

Yes

There is no such thing as cheap gaming pc.

I prefer to call them inexpensive, but yes, they have gaming laptops and pretty good service available to customize them for you if needed. Speed up your gaming laptop by having them put in an SSD and some additional ram.