CRF230ripper, while some of your points are valid, there are a few holes which I feel should be mentioned. First, you seem to be basing you 4-stroke knowledge on the 230F, which is virtually zero maintenance, but when you move to a CRF250R, you WILL find a huge increase in maintenance. It's the nature of any high performance engine. Also, the OP has expressed an interest in a 250 and not a 125, they are different animals as well. The bigger engines have much better bottom end torque, and can be lugged around more. Also, the big bore bikes seem to require a little less maintenance than the virtually extinct 125's. For a rider on a budget, a 250 smoker is probably the way to go, especially if that rider is over 180lbs.
To the OP, don't be mistaken, a properly tuned 250 2-stroke will give you whiplash if you twist the grip too hard, so don't be stupid if you get one. Research the engines and try to find something with a broad smooth powerband. Don't worry so much about top end power.