#1. Korg is a much bigger company vs. Ketron.

#2. The PA2X is based off of the previous PA1X keyboard. There is zero physical difference between the two. The same metal case to make a PA2X is the same as PA1X. This cuts down on cost. Korg's technology is basically carried over from previous technology.

#3. Audya is a completely new development of their arranger product. Ketron being a small company incurs a higher cost of development.
If the made a SD2plsu to replace the SD1, than the cost would be cheaper.

#4. When the Audya was launched and introduced, it came at a time when the US Dollar and Euro was weak and probably is still weak.

#5.The keyboards do not sound the same.
For the people who choose Audya over Korg the price is not as objective. They'll pay more for the product that they feel is going to make them sound better.