The number of buyers is of course not yet known, just like any new "niche market" product. Some of you may be surprised, horrified, and disappointed, but unfortunately Pete did not spend $50 Million to do a Rand Corporation global market study like Coke or Pepsi would have on a new product.
Anyone wishing to estimate the size of the market should consider this:
First, the engine as it stands now is a viable replacement (viable... not perfect in every way, but competitive on at least two or three levels) for 52-64HP Rotax 2 strokes, 45-65HP Volkswagen derivatives, and a small percentage of aircraft with Continental or Lycoming 55-65HP "airplane" engines.
Second, the size, weight, power, and trustworthiness will create viable opportunities for the modification/updating of existing E-AB designs... and for new "clean sheet" designs.
To my best guess, that means there is certainly at least 20,000 possible customers, let's say half of those would be halfway reasonable, and one out of ten of those people would be realistically able to spend the money on a replacement upgrade engine.
So that would yield a conservative guess that there is a viable market of 1,000 engines. I think it's likely more than that, but I am totally and admittedly biased in favor of this product.
The fact that an O-200 weighs between 225 and 190 pounds depending on stuff installed or removed is irrelevant. The fact that there is an engine that weighs "around half" of an O-200, and still (very likely) has all of the reliability and safety... that is why the engine has generated so much interest.