David,
You very well can save money, but you'll invest a lot of time. Trading labor for money is a fair and time honored tradition. A completed RV-7 seems to be selling for $20-30K more than the build cost, from what I've seen recently (which works out to a pretty low wage). You'll also be able to spread the cost over a longer period of time. Most importantly, you can build WHAT you want, the way you want it built. And an RV can be an amazing flying machine.
Having said that... do you plan to be in one place for the next several years? Are you willing to devote most of your recreational time to building? If you're going to be moving, you will NOT want to move a partially built airplane plus all the tools and parts. I know others have done so, but I would not start building unless I was sure I was going to be able to finish it in the same place. Yeah, the rolling stone vs. moss thing.
Of course if you want to get a taste of it, come on down and help me rivet wing skins and finish my flaps. I'm about 2 weeks behind where I wanted to be right now, I want these wings out of my garage before July (probably not going to make it). If you want to rivet while I manage the bucking bar, I can get back on track... and you'll either fall in love with building, or decide on something else.