Just a thought about the machinery. Someone earlier posted that older/prepped bikes are far less money to "race" on. This forum had a very nice 500 twin just a few weeks ago, went for around eleven hundred, I believe. While not an hp king, it IS eligible for...Lightweight Endurance, Lightweight GP(easy to get novice waiver from New Rider Director), Super Twins U, Novice U, Amateur U, Colorado Class, and of course, Sportsman.
I went the pre made route three years ago. Actually, it was four. I raced Sportsman Motard on my dirt bike for a season. Cost one set of tires. Still got them. Decided to learn to drag my knees. Bought a GSXR600 for 2500. Fully prepped, rear sets, ect(and spare motor of questionable heritage). Rode it for a year, sold it, and bought an SV650 for 2980 (which included the 490 for shipping). I've been racing it for the last three years(I did put flat slide carbs on it last year). Tires last a long time and maintenance is next to nothing.
My point(finally) is this. If you can live without the lastes and most expensive machinery and learn the basics, it can be done relatively inexpensively.
Of course, inexpensive is relative. You can spend 600 on hiking boots, so???
I really hope the intro class idea gains traction. Like Beuller said, Heroin....Cheap!