By the DMG equations the cost of an item that lets you quicken dim door at will would cost 216,000. Also since the item has 5 charges, it would cost the same amount as at will. (This is a generalization of the magic item creation rules that one should evaluate for the item that you are creating. That is to say determine the point in which X charges is equivalent to at will) Since the range at CL 7 is 680 and the items range is 60, It is 1/10 as power. If we assume linear power progression the cost should be reduced to 21,600. Since the MIC considers 5 charges on this type of item to not be equivalent to at will (I would agree), it would be further reduced. I cannot see the factor being more than 10 rounds (3 combats a day, 3/4 rounds of combat). Thus the resulting value should be somewhere between 10,800 and 18,000.
The point of contention that I see in this is the assumption of linear power progression. Dnd follows an exponential power progression. I believe this is a reasonable assumption in this case since there are two exponential progression (cost of the item and power of the item) that are in conflict with each other. This still assumes that they have the same progression, but since there is not a factual method of determining their progressions, I do not find the assumption that all progressions in dnd are relatively equal outrageous.
