This variant is born of a rule misunderstanding but still provided a good game. Instead of looking to the bank to determine tile cost, look to the remaing tiles in the stores.
The way we played:
Instead of using the bank to determine cost, we used the tiles remaining in that particular store. So at the beginning of the turn, tiles cost 4. If one has already been purchased, the next one in that store costs 3. If two tiles remain, the cost is two, etc.
I am going to try this every couble plays and see how it changes the game's play.
Other ways this rule may be adapted: - Untested
a) Tiles cost 1, then two, then three, etc. as the store runs low on goods. This would allow you to force people to pay more and would give the person that starts the next day a big opportunity.
b) The tile cost progression is the same as in the first paragraph except you use the other store's progression as the meter for cost.
Store A has 2 tiles
Store B has 4 tiles
A Store "A" tile would cost 4 and a Store "B" tile would cost two. This would encourage more balanced buying and mix it up a bit if one store had prime goods and another not so hot.