Kondo Audio Note Io ii+ Kondo AN S 7 II - Keep it or sell it?

Things simply keep accumulating. At the moment I have both these pieces lying around in a drawer. I am in a quandary, because it is simply a shame that they are not being used. I assume that they will not depreciate in price, but what are the chances that they will appreciate?  

To put it in other words: Do I try to sell them now, or do I leave them in the drawer? 
Are these the rare field-coil magnet cartridges?
No. The Io ii is an old Japanese-made Kondo cartridge from the early eighties, and the S 7 is the matching SUT. I dont know how collectible these are, which is why I started this thread.
Definitely collectible! And very desirable as a pair! Price? Needs some researching!
Well, they are pretty rare, and prices are all over the place. That is part of the problem, there simply isn`t much information on the internet. 
As you say, probably quite desirable as a pair. The question is if they will appreciate in price and are best left in the drawer, or will the cartridge be better off being used.
I'd sell it. The AN S 7 II was surpassed by the KSL-SFz, which I owned both. I just sold 2 of my KSL-SFz step-ups for a superior sounding SUT out of Russia.

(Disclaimer:Former Kondo Distributor)
Thank you. I will mount the cartridge and try it out again before I decide, but you certainly have given me food for thought.