My name is ***** ***** I would be happy to help with your beautiful teapot.
These remarkable examples of the brass and coppersmiths' art are always met with the reaction you've already gotten at most antique shops. Everyone thinks they are splendid, but nobody seems to know where they come from or anything about them.
I've seen this dragon handled, moon-flask ewer style vessel described as everything from Persian to Afghan to Burmese and Chinese.
It's actually Tibetan in origin and sometimes called a "wine ewer" rather than a "teapot" as this form was used for wine originally. Another typical Tibetan decorative motif is the cone-shaped base adorned with a lappet band of stylized leaves.
Yours dates to the first half of the 20th century, most likely 1920s or 1930s. One can date them quite well by the quality of the decoration and engraving and particularly by the neatness (or lack of it) of the pierced decoration in the center. For instance, you can see on yours how many of the holes have bits of sprue (metal that seeps out of gaps in the mold during casting) that would normally have been filed away or removed on 18th or 19th century examples, but left unfinished here.
As for value, for some reason these have never gained much traction with collectors here in the West and considering all the workmanship and artistry, prices for them are remarkably modest. This similar example to yours, for instance, sold at auction for only $80.
I would give yours an auction or online (eBay etc) value in the range of $80 - $125.
It would therefore have a full retail value (if you saw it for sale in an antique store, for instance) of $250. This is also the replacement value for insurance purposes.
I do hope this helps! And you won't shoot the messenger about the value! You'd be doubly bummed if I'd given you false hope and told you it was worth thousands if and when you ever came to sell it.
Please let me know if you'd like me to explain or expand on any of the above, I would be glad to.