though. Use PCPartsPicker that'll save you time on the research side (is it compatible, does it fit, where can I get it cheapest, what are the alternative parts, etc.). Also, other people publish their builds.

Assembly is pretty easy. Nothing there that you can't learn quickly. You can run into odd things about parts not quite fitting or wires not going where you want, etc. but it's never too bad.

As for is it worth it? The time isn't too bad, particularly if you are vaguely interested in it and can write some of it off as a hobby vs chore. As you surmised below, you probably won't get better prices on parts than some manufacturer (though you might if you are patient and wait for sales), but you will pick exactly the part and where the budget is spent.

I just looked at Dell XPSs in the price range I spent on my latest build and I may have come out ahead to the tune of $50-150.