Level Min. Skill Loot
1 52.0 0 to 60 gp
2 72.0 98 to 125 gp
3 84.0 200 to 350 gp
4 92.0 500 to 900 gp
5 100 don't spawn in dungeons

Skill Training
You can get up to 95.0 lockpicking with GM Carpentry/tinker made boxes (As far as I know only the tinker skill of the maker of the box determines the lock strength. Since lockpicking is target based, you need lots of boxes. The easiest way to organize them is in bags of 20, with a key ring holding the keys to re-lock all the boxes (key rings only hold 20 keys.)
After 95.0 lockpicking you can only gain by unlocking spawned chests in dungeons and towns