well, that's good about being a thief....and with the help of some invisibility scrolls... that guy in Sadrith Mora - Divayth Fyr I think his name is. A very high respectable temple guy, and he's got TONS of valuable stuff. Yesterday I stole a cuirass worth 150 000 gold.... and I sold it to the museum of artefacts in Mournhold
anyway, I think you should steal some there, but you should be able to open lock 100 and so on
btw, The fighters guild in Ald Ruhn also have a whole glass armour set if you're interested
lock level 50 or so