Hi,
I have seen several Bellin maps at various antiquity shops including a specialty shop in Toronto.
The maps are move valuable if they have ORIGINAL colouring or no colouring at all and of course if there is not a great deal of "foxing" or wear and tear.
The maps value differ according to area of the world. Generally speaking antique maps of the "New World" are more valuable and collectible however purchasers often will buy a map for local interest.
Bellin was a highly skilled French Hydrographer and has produced some very fine maps, especially larger pieces.
I have a small Bellin map of the Hudsons Bay region in canada and I like it. I would consider buying more if you have any other Canadian pieces.