This phenomenon isn't uncommon among the Indian States that I collect. Generally speaking, the stamps issued by the States were valid only within the borders of the States. Combined with low rates of literacy, you had the recipe for low rates of usage of the stamps.
Mint copies could be relatively easy to come by: the dealers would be able to buy them from the State post offices. This 1931 1 Anna rose-carmine of Barwani State

is priced at £18 mint in Gibbons - but at £65 used, and £195 on cover. There were no stamp dealers living in Barwani.
Some of the States woke up to this. In Sirmoor State, the State postmen were under instructions to recover the stamps from all mail they delivered. As a consequence, used stamps of Sirmoor are quite common - even though Sirmoor was not a large or important State.
I have no
proof, but I suspect the same system applied in Jind State. Used copies of this 1882 ½ Anna lemon on thin wove

are cheaper than mint (£3.50 for mint against £2.50 for used), but I wouldn't accept £500 for this cover with the stamp

In 1931, Charkhari State released a set of nine pictorials, ranging in face value from ½ Anna (the basic letter rate) to 5 Rupees (180 times the letter rate, and quite useless as a postage stamp). The set was dumped on the market CTO

and Gibbons still price the whole set used at just £2. Charkhari fairly quickly withdrew the stamps and replaced them with much less colourful items. However, genuine usages of the pictorial set are very scarce, and covers

even more so. Even fairly humdrum genuine covers from Charkhari aren't at all common, of course. This ½ Anna red-brown of 1940 rates £6.50 mint and £30 used

- and £90 on cover.