2nd hand jap bikes in that price range have all been abused to within an inch of their lives
if you buy something in the sub 15k bracket look at major repairs coming your way
old xt600's etc great bikes but factor in a full engine rebuild - if its old it will break
chinese bikes are not that bad - mine has almost 18000km on the clock and no major hassles
parts are dirt cheap

you can look at the xr125 - but that is just another chinaman bike with a honda badge on it
the new honda e-storm, xr, etc are all being built in china to compete against the chinese
the old cg125 was more expensive than an e-storm - why

because it was better quality - the new honda cheapies are no better than chinese bikes