Thing about a ttr or crf 230 is what ever you pay(well as long as you didn't get ripped off) for it, you can likely sell when you're done with it. The wife bought a crf150f, rode it for 2 seasons and sold it with $100 of what she paid.
Maintenance is dead simple with those bikes due to the fact that there is none.
If the person decides at any point down the road they want a nicer bike or they are not interested in the sport the losses will be next to nothing.
A 250f is pretty high on the maintenance and if it blows up, well it will likely only be worth parts after the fact.
Having said that, my 250f has been awesome.