1) Pics are great when you don't have a scanner. But for detailed examination of stamps and such, scans are much better at showing the deatils.
2) Post a topic out in the reguular area of the forum, so more people will or read what you are asking. Better exposure that way for you.
To me, that sounds like a hand-drawn hand-painted (HDHP) cover or first day cover. Or, at least a limited run production of a first day cover.
Search for hdhp on
ebay or the full words on Google to see many examples.
If the art is nice, that makes it worth more. The eye of the beholder and all that.
And if the topic is appealing to many people then you have a greater appeal and more bidders on an auction sale, or a dealer can ask more and get it for that particular item.
Everything is worth something. Part of the trick of stamps is finding the right people who are interested in that stamp or area or topic at the time you want to find them. So, it is best to know a bit about your stuff so you can advertise on
ebay) with the right words or know that it is not just a cover but an original hand painted, sought after, super dooper what-his-name cover (hopefully).
Dealers won't give you much as they have to sell it again themselves. If you don't want to sell it yourself then you pretty well have to pay someone to sell it for you. On consignment, outright purchase from you, etc. Basic financial math. Don't mean to turn you off of stamps here, just to know what you are getting into kind of and be aware of how different buyers would think.
Perhaps I have rambled on long enough for now.