Malletkat Pro - value help?

I am contemplating selling a Malletkat Pro that I got for my son back in 2009 that I've had in storage.
It includes the 3 octave body, plus (2) one octave add-ons......5 octaves total. All notes work fine.
+ Foot pedal, cables, manual, wall wort power pack.
When I turn it on, it says it's version 3.6 YWS
What should be the asking price? I've had a hard time finding any history of sales on these.
thanks

Update: I checked Alternate Mode KAT's website. Looks like I can get the chip that upgrades the MalletKat from V3.6 to V6.1 for $179.

Would that be a wise investment in order to sell it, or just leave that up to the buyer?

Would it make sense to sell one or both of the octave add-ons separately? Is there a market for those?

thanks