Rocketman - The completely unadorned "Black Widow" guns can be masterpieces, too - shape, balance, fit, feel, finish, etc.
OB - Probably as many ways to calculate an engraver's fee as there are engravers. Some generalities do apply: Best engravers cost more than so-so engravers.
Generally, the engraver has to make enough to feed his family and pay the rent. Coggan made the comment once that he had spent as much as 10 months on a single job. I don't know if he had any other jobs during that period. If this was the only source of income for the engraver, he has to earn at least as much as any other skilled craftsman, say a furniture maker, a stonemason, or a machinist.
Typically, an engraver will give a client a lump-sum quote at the outset, and will ask for a percentage downpayment before starting. The payment of the rest of the fee is due upon completion, or in instalments (for very complex jobs).
Stallones - I no longer build double muzzleloaders. Too much of a problem with TAF. They are trying to classify engravers and stockmakers as "manufacturers," and a manufacturers' license is a whole lot more expensive than a gunsmith's. I still like to shoot them, however, and if you have a specific question, I'll do my best to try to answer it.
Jay Cee - I mispoke. The book with the Mountbatten portrait was "The Art of Engraving," by Gaier and Sabatti. I'll need to learn to check my sources. It is a nice, slick picture book, however, with work by Ken Hunt, Coggan, Fracassi, Creative Art, and others.
Bill