Sounds as though lockpicking has changed quite a bit since I did it.
I got to 36 in towns (prov. shops, barrels on docks, inn chests) then acquired a set of boxes to take me to 95 skill. For my last 5 points I went to Destard and gained them on chests there. Some of the boxes we have SHOULD be gm made, but I know we have had a few pickers who couldn't gain to gm with them, so I sent them to try the gypsy ones instead, and they gained.
@Tjalle, if you want to use the boxes we have at NEW you're welcome to, just have one of us friend you, and if anyone has a few gm boxes they could let us have to save a NEW from hunting about for them, they would be most welcome. The set we have at the house is the same one I used myself, and they fall short of getting you to gm by the 5 points.
Thanks much