I built a gaming PC about 18 months ago. First time build and it went smooth as hell. Haven't had a real problem with it yet. I ordered everything from Newegg. Spent a few hours one night with a couple of buddies putting it all together. They didn't have much experience either but we made it work. I ended up spending about $2k total, but that includes absolutely everything - the entire rig, OS, two 24" monitors, mechanical keyboard, decent mouse, and shipping costs for all the components. It was/is overkill for what I do, but it handles everything I throw at it without complaint and I haven't had to upgrade a thing yet.
Some tips from my experience...
-read. Read. And then read some more. Since you're doing it down the road, that gives you plenty of time to plan. Read product reviews. Check out forums. There are websites dedicated to making suggestions and helping out new builders. If you read a negative review on something, don't panic and dismiss it. Many gaming PC product are pretty specialized and that means that they may be designed to appeal to a specific demographic or work ideally for certain purposes. And sometimes the product is just crap. One bad review doesn't tell you that, though - many bad reviews does.
-as already recommended, videos are a great tool. Fantastic. I was way more comfortable with the assembly process because of the number of videos I watched. While assembling, my CPU cooler came with terrible instructions but I found a great assembly video on the manufacturer's website. Problem solved. I also found the manual for my motherboard in PDF form on the manufacturer's site and spent some time reading it before I ever got the motherboard. Due to that, I was pretty familiar with all the wiring hookups, which is probably the most complicated aspect of a build.
-when planning, be realistic about what you want to do. That can save you some money and effort. If you don't ever plan to overclock, an aftermarket CPU cooler really isn't necessary (unless you will keep the system in a really warm environment). If you change your mind, you can always install one later, but that usually means pulling out the mobo. Whereas adding additional RAM is usually drop in and very easy (unless your cooler covers the slots). Adding an additional hard drive is usually very to install so long as you space for it.