Valuing and Selling 1917 Russian “Currency Stamps”?

[Octoposse]

Having a good sort out of clutter, and found a dozen 10x10 sheets of what I think are 1917 3 kopek currency stamps, unused. One of my wife’s car boot triumphs from a few years ago.

Want to clear out the wardrobe, and hopefully put a few quid in the kitty, but can’t find anything similar to give me a guide price.

Anyone any pointers? Happy to put them on EBay, but don’t know where to start.

[Simpo Two]

Whole sheets of unmounted mint examples... it seems unlikely there are many of those.

Here's one on eBay: https://www.ebay.co.uk/itm/350367291608

Also https://rusphil.com/russian-empire-1857-1917/russi...

Of course they might be forgeries!