Nice! I keep meaning to get one of those.
There's not a huge amount of Namor merchandise out there, though a good portion of it is the old, Marvel Mania stuff, and thus pricey. Though there appears to be some knock offs / reprints that are more affordable.
No, I don't think there's one for Doctor Doom. There was only a coin for Cap and for Subby, in two collector's set. This coin came out with a VHS set, and IIRC, a Steve Rude print.
... Marvel's Mightiest Super Heroes features: Avengers print signed by Steve Rude, Reprint of Journey Into Mystery Comic Book, Sub-Mariner Collector's Coin Three VHS tapes featuring digitally remastered cartoons from the 60's: The Amazing Spider-Man The Mighty Thor Sub Mariner
https://www.worthpoint.com/worthoped...est-1627446929