The whole inflation thing in my opinion is a affected by a lot of things.
Game does this so you have to change gear often. This leads you to having some skills in earning money or stealing. Another thing is that there is no way you can find an op item that you can keep it for a long time because after couple of levels it will be obsolete. At first i didnt like that thing but then i realised that this is how the game works. Its one of the things among others (like the way armor works) that makes this game unique. I dont mind spending some time to buy new items every couple of levels since this + lucky charm works fine by me.