Ahhh, the lure of the E30...Hey Brian, tell you what...look around southern Florida and find either a '91 318iS, or a '89 or '90 325iS and go for a test drive....
You'll find that parts are plentiful, reasonable and they're ready for autocross out of the box. With a garage and a few tools you would be able to keep within a tight budget and tweak it to your liking.
Or you could move next door to me and I'll introduce you to the "wintertime sanity" program, and help you with it. =)
Keep reading those articles, there's good information to be gleaned from them. Take a couple of test drives in 13 year old technology and see what you think. They are basically pretty simple to work on, and you already have an understanding of how BMW's work, so why not? If you look at the 325's then be sure to see if the timing belt has been replaced as it should. Com'n in, the waters fine!!!
Jr