So when I'm at the shopkeeper/armorer in Oxenfurt his stock changes when I exit the screen and start the dialog again. The available armors changes and also required levels. Anyone ran into this to?

Happened to me once too. I was leaving the shop to double check the stats on the specific pieces of armor I was wearing (fucking crazy this info isn't presented in that menu, btw) and when I went back to buy a diagram, it was missing.

The weird thing is that it happened over and over again. The shopkeepers stock changes ten times over, with new armor and the levels changing every time.