It's not a lot cheaper to be honest and if you get any problems it's on you. But really down to your level of confidence building and maintaining a pc.
Scan.co.uk get yourself a pre built if you haven't had experience of building and maintaining a pc. The main thing that will drive the cost of the pc will be the graphics card. Nvidia graphics cards are the main player. The latest cards are the 40 series cards and are top dollar and can be...