Cline, unfortunately I don't know of a good kart forum. It's an area still mostly dominated by circle track stuff and thus rednecks who misuse terminology and thus make Google searches useless and annoying at best.
There are a few people in THSCC going down this path, so maybe start a thread here. Or go over to RoadRaceAutoX for this thread:
http://www.roadraceautox.com/showthread ... ooresvilleBest thing you can do is go to the track. Head down on a weekday and do three pops in the rentals. You'll find a *real* race track. Or better yet, go on a Wednesday afternoon. Do a few rental pops before 4pm, then stick around that evening for the show. They have rental racing (hell, sign up and do that!) mixed in with TaG kart racing. You'll see NASCAR, F1, etc drivers out there. Denny Hamlin, Scott Speed, and Nelson Piquet Jr have been out there the last two weeks (only three weeks left of the current series).
Don't let the prices of the new kart packages scare you off. A new setup from those guys at the track is $10k. I bought a very nice used package from Brian Smith down at CMP with a fully fresh motor for under $6k. You can get started even cheaper than that if you really want, too.
One thing to keep in mind is that karts are BIG. Way bigger than you think, anyway. You won't fit one inside a normal SUV without taking bumpers and side pods off, but that isn't TOO bad, anyway. But even still, racing that way is tougher as you also need a kart stand, tools, etc. A small enclosed trailer is better, but poking around can even find you a setup kart trailer pretty cheaply. Good used enclosed trailers suitable for this are around $1k to however much you wanna spend.
Last, there's a LOT more to kart setup than you'd think, unfortunately. A LOT. That said, there are a few guys around MMX who are REALLY good at kart setup and you can pay a little money to one of those guys to get you in the ballpark. Then just go drive drive drive. Drive a LOT. And then start doing your own tweaking and learning what the different changes actually do. Ultimately it isn't too bad, but looks pretty daunting to start.
The beauty of MMX is that even if you aren't doing any of the membership things, it's only $60 for an unlimited day at the track. That doesn't mean completely unlimited track time, however, as they do still rotate 10 minute sessions. Most days you'll just be 10 on and 10 off from what I've seen (swapping with the rentals), but sometimes there's a third kid session mixed in.
Unfortunately, TaG karts (the most popular by far at MMX) aren't very useful for autocross if you want something dual purpose. All the autocross karters are in shifters, which is sooooo dumb, IMHO.
--Donnie