I'd look HARD at the CR125 Elsinore. Those little 125 buzz-bombs can be VERY fast, but maintenance is intensive since you're revving the engine to the moon, and shifting all the time to keep speed and momentum up. But they ARE tough, and they redefined the small-bore MX game. They can be THE ticket in 125 Sportsman, and with upgraded shocks and forks, handle "period" whoops, jumps and berms with aplomb. Lightweight, good-handling, with a tough, user-friendly engine that has plenty of power in a wide, smooth powerband.
Everyone seems to want the 250 Elsinore, (a fine machine) but the demand has made the 250 more expensive. The 125 is just a sweet little jewel. Fairly cheap to buy and not bad to run. There is a huge following for them as well.
You could get the 125, race it for a season or three, then get a 250 when you feel ready, so you can enter in multiple classes for MORE racing!
If I wasn't so stuck on the Hodies, I've have an Elsinore or three myself.