Uniqueness can be a strong selling point.
If you are a would-be buyer who just wants the functionality of the SX-32 Pro ,then the collectors' value is a bother to you.If you are whining about the SX32Pro being less functional than some other cheaper solution,then why not use that other solution?Unless you are hoping to get the rare item for a price based on functionality and then also have bragging rights to a rare item.
I admit to wanting an SX32Pro myself but recognize that rare collectibles will be bought by those with way more money than me;just as I found myself being outbid on old radios in eBay auctions by rocker Joe Walsh.
I'd love to see someone market a modernised CD32 expansion unit equal to,nay superior to, the SX32Pro.It would seem that if a C64 could be made in a joystick .....