How to handle non-existent SKUs in Expresso Store - expressionengine

Question

I'm using Expresso Store for a clothing retailer. Several of the products have color and size options, and generally I think Store does a good job of handling these. However, when I add multiple modifiers (such as colors black and red, and sizes small through large), store automatically creates individual items for each combination, and requires a unique SKU to be entered for each one. The retailer, however, stocks several items that they carry in all sizes for one color but limited sizes in another, and therefore doesn't have a SKU for the sizes they don't carry in that particular color. For example, they might carry the following in their inventory:
Red size 2
Red size 4
Red size 6
Black size 4
Black size 6
In this case, if I add "Red" and "Back" as options for the color modifier, and "2", "4", and "6" for the size modifier, Store automatically creates all possible combinations, including Black size 2, which they don't carry and don't have a unique SKU for. In this case my workaround has simply been to enter in a random sequence of numbers/letters and set the stock level to zero.
Is there a better way to handle this? Could there be a way to indicate in Store to indicate the retailer doesn't carry a certain combination?
I'm not sure that this is a common problem, as I'm guessing that larger retailers would carry the product in all size/color combinations and thus have unique identifiers in their system for each. But wanted to relay this as it may help a good product become even better.

Answer 1

There's currently no way to "disable" a certain SKU, or leave it out from the stock matrix. The best solution is probably what you are doing - simply make up a SKU, and set the stock level to 0 which will prevent it from selling (and allow you to display a message to customers when they select this combination).
Even if it were possible to disable a SKU, it would make front end templating tricky, because you would need to dynamically change which options were available in your select drop-downs (for example, hide the "Size 2" option when they chose "Black" in the first drop-down). This wouldn't be ideal from a UX perspective, because the customer might wonder why size 2 isn't an option, and not realize that size 2 is available for the Red version (so it's probably actually better to just leave it there as an option, but display an out of stock message when they select it).
The other option to overcome this is to just use a single modifier. This makes it clear the "Black Size 2" isn't an option. For example, just create a single modifier called "Style" with the following options:
Red (Size 2)
Red (Size 4)
Red (Size 6)
Black (Size 4)
Black (Size 6)
This way your customers will only see a single drop-down on the front end, and it won't be as confusing for them.