Not so fast, clueless(builder) one! There are other voices in this wilderness.
TIG is wonderful. I wish I could do it well. But, here are a few things to consider
in the short term of getting going with your build project.
1) TIG is slow! MIG is fast.
2) TIG takes real time to master, MIG is much easier to learn and do well, but not trivial, so give it some respect as an achievement. It can be done beautifully and with strength. Check out this MIG like TIG thread in the Welding Web forums.
MIG like TIG (page 2, there's a lot more on page 1 too) ==>
http://weldingweb.com/showthread.php?30 ... -Tig/page23) Even with a chassis rotisserie, you'll need to do out-of-position welding and MIG is much easier to do that with, particularly for the novice welder.
4) You're going to be doing a lot of different stuff, like building various pieces of infrastructure, jigs and one-time-use parts and various small tools where MIG is a more appropriate process than TIG just because of the time and trouble TIG takes to set up and do versus a quick application of MIG. With MIG you can tack weld easily and quickly too. You'll also do a lot of that.
5) MIG is less expensive and you can weld longer too. The MIG gas is cheaper. The MIG wire is cheaper. If you screw up, you don't have to regrind your tungsten 'cause you don't use any with MIG. Regrinding tungsten gets real old and is a constant interruption of your processes if you're learning and a real nose bleed IMHO.
I say go MIG
now and aspire to do TIG, but don't make it your first welding process when starting out on a Locost project. I pass this on from my own experience. I tried to start with flux core because I was on a strict budget - don't bother with flux core and thin steel unless you are total masochist. I switched to a scratch-start TIG system (budget again), but discovered what a slow and demanding method it was. So, I switched to MIG and bought a small, but high-quality MIG welding rig, which really made things much easier and faster.
Good luck with whatever choice you make, however.
Cheers,
Lonnie