Replying to Recommend me a first dirtbike!

I'm looking at getting into motorcycles, more because its something i want to be able to do and do well. not to cruise around on my R1 with cargo shorts and backwards hat. but get to the point where i can get myself around an MX track and maybe do some track days on a sport bike eventually.

I figure a dirtbike is a good starting point to get the feel of the bike moving around and sliding, get my control skill set dialed, do some jumping, etc.. plus it just seems fun.

I've got some basic experience on a pit bike, some friends dirtbikes, etc. can get around somewhat difficult terrain and have the controls down well. and do a ton of mountain biking, so im not a complete noob but definitely not good.

I dont think i need anything with crazy power or capabilities. but would rather have something easy to control, whip around, find its limits, etc..

I'd like to keep the cost under 2000, less is obviously better especially if i'd be upgrading after a while.

so far people have recommended a klx140, tw200, yz250/other 250's

any thoughts?