I'm not really in the circle, as far as Era goes, but perhaps instead of a generalized "purchase completed weapon" system you should use a frabrication system. That way the components have an individual value, giving the final product a value (whole is equal to the sum of the parts :P).
Having luxury items isn't a bad thing, especially in the competitive environment of a game - it's desirable. Sounds more like there's a class gap between item values... either because of set (intentional) prices or because certain statistical nuances (availability, item specifications).
In my opinion manipulating the value of any item, as initially suggested by the original poster, is the worst thing you could do. What I mean by this is altering the value which has been determined by players. It undermines the role the users play in the economy... since they're the driving factor that's a pretty bad idea. After that you're just pissing people off; they have "assets" they understand to be a given value which will either slowly depreciate (increase in value), or if they're lucky, appreciate (increase over time).
To change it dramatically would have the following effect on your playerbase, and given that they're mostly male, you could expect hard feelings:
