If I may suggest something. I think you should split the set into two kits, like you have now. But make one kit the Alphas plus oddball compatibility, like ISO and 1800. Make the other kit the Mods plus Tsangan, etc. That way, people who already have alphas only need to buy the mods set, whether they have a standard 87-key layout, 86-key, etc. And the people who want less popular kits like 1800 and ISO get to have their kits subsidized by the popularity of the alphas set, and are also required to support the GB by buying the alphas. Just my opinion, but that's how I would do it.