Personally, I think it's a really cool idea, and even cooler to be able to have something physical related to MD.
Financially, I have to say no.
The "find the middle-ground" part of me says... start small. I don't know if or what current land leaders have in their real-life possession to represent MD, but there are some ideas that can be taken from the big idea and built around, such as the wax stamp. That's the one that really would be something special to me. For little to nothing (if you know how to work wood and/or have access to anything to carve out the stamp part) you could make these yourself and send them out, only real price would be the shipping involved. Also, if the king ended up keeping it, instead of passing it on, then you wouldn't be out the expense of purchase, just the time it took you to make and whatever shipping is. The wax... well, that'd be between you and the ruler to decide who purchases that I think. Some players are well funded, where as others are not. MD/You could help out who couldn't afford to purchase the wax themselves, but encouraging them to make that purchase allows for them to personalize that part of their kingly stamping/sealing documents ability.
So far as the King specific stamp, for regular ink, i know those can be purchased US for maybe 5 dollars. Unsure of the cost of UV specific stuff, as I've never dealt with it.
I also like the idea of the papers but for now, I can't think of a cost-effective way to do this, other than building a sharable document, and they can print them off as needed on whatever type of stationary/paper they choose.
All in all though, I really do like the idea, but with as small as MD is right now, i'm just having a very hard time justifying the expense. If none else, it might be best to keep it in the "when we get big again" pile.
**edit, I was typing this as Mur posted and didn't see the post til after i posted this. sorry.