More Talkative Thomas, how rare is it, and if there are more out there somewhere.

The 2nd generation “more talkative” Thomas at the Coal Hopper set, isn’t really as rare as it is expensive… There seems to have always be one up for auction somewhere over the past 10 years, and I have seen many on the Japanese auction houses and eBay, however it’s the price that has gone from a BNIB set costing around $50, to it currently fetching $1500!!
It’s a weird designed engine, and being tender driven (the Percy model is also) probably wasn't the most popular of Thomas versions.
Is sad because the other “more talkative”characters: Gordon, James, Henry, and Edward are all conjoined 3 piece units, and are among the greatest designs and quality that Tomy ever produced.
https://www.ebay.com/itm/More-Chatty-Tho...632-2357-0
https://www.ebay.com/itm/Plarail-More-Ch...632-2357-0
https://www.jauce.com/auction/u131327392