Used 4 stroke repair costs/risks?

a 250 2 stroke isthe way to go. You lucked out with your woman

I wouldn't recommend buying a used 250 four stroke - the reliability isn't there for those motors since you have to run them really hard and you roll the dice on having to rebuild something soon after your purchase ($$$$). I personally wouldn't buy a used 250F. A 125 is going to be pretty low on power for your size. A 250 2 stroke would be a good choice and cheaper to rebuild/maintain. Good luck!