I'm thinking about building a desktop PC?

I'm looking to get a gaming computer, but I heard that building one yourself is a lot cheaper than buying one. The biggest game I'm planning on running is Skyrim, but I just want something that can run mostly small games like Terraria and Minecraft, games that I can pass time with. Can anyone help me get started?

You must heard from a guy from the 1990s, back then its cheaper but now its way cheaper to buy a pc off the shelf. You can buy a decent pc to play games with dedicated graphics.

I got my laptop for $700 and its pretty fast, it can open photoshop cs5, lightroom, and still have my starcraft 2 game out with no problem

Buying parts separately is costly to the point that I would rather buy a new pc then replace a part.

Considering the problems that might occur with compatibility issues buying a machine may be cheaper in the long run these days.
Here are the specs for a Skyrim game. You will want to check out the specs for newer games so that you don't build a obsolete machine. Remember, Windows 8 is NOT a good operating system when playing the older games (those not programmed especially for it.)
Skyrim Specs: (Video Graphics is where most machines fail the test)
You Do need a machine that meets these requirements for Skyrim.
Recommended
-Windows 7/Vista/XP PC (32 or 64 bit)
-Quad-core Intel or AMD CPU processor
-4GB System RAM
-6GB free HDD (Hard disk drive) space
-DirectX 9.0c compatible NVIDIA or AMD ATI video card with 1GB of RAM: Nvidia GeForce GTX 260 or higher; ATI Radeon HD 4890 or higher
-DirectX compatible sound card
-Internet access for Steam activation