I bought some Acerbis handguards for the 125SM. They fit well, with great clearances. However, because of the anti-vibration damper inside the handlebar, they must stick out 1" on each side (this also helps the levers clear the guards).
I got mine at a local Cycle Gear so I could easily return them if they didn't fit. If I had to do it again, I'd get it from Motostrano:
http://www.motostrano-store.com/acraprobrgu.html
Cycle Gear only had them in blue, but I had a can of black paint (which solved the issue of what to do about the Acerbis logo!). I'll post pics once the paint has dried and the handguards are reinstalled...