While building a PC might seem like an easy task to do, it's really very confusing, especially when you don't know much about what you are doing. I am someone who prefers to have a pre-built PC even if it costs me a few more penny than it normal would. But there is no doubt that you would save some money if you know how to build a good gaming PC.
I think that building your own PC is a very good idea because you can choose your PC to exactly what you want, for a cheaper price. Also, I think it is really easy to build a computer, as most items even come with their own instructions. Plus, you can even have the appearance that you want, which is something that you don't get with pre-built PC's. If you need help, there are plenty help in forums if you do a quick search.
Sure it probably does save you a lot of money but i would never attempt to build my own PC. I can never do that even if my life depended on it. Imagine if i tried building one, so i got all the parts needed and i start the whole building process and then bam! I messed up and then I'll get new parts to replace the things i broke, which just doubles my expenses. I'd rather not go through that whole thing. -.-
While building your own computer is definetly the way to go, I wouldn't agree at all with the notion that it doesn't take any experience to build your computer. It's not as easy as putting Part A into Part B. You actually have to have a decent understanding of computers and how the parts work with one another to make sure everything is put together properly and the way you want. I believe it's like $50 or so to have someone at Best Buy or Fry's put it together for you. That's what I did with my computer because 1. There wire set-up is so clean, it makes swapping out hard drives, RAM, etc really easy to do and 2. I know it's done correctly and don't have to worry about any potential mistakes I made with putting it together myself. It's still a lot cheaper than buying a pre-made PC and you also get the benefit of picking up some basic computer knowledge along the way.