I have a 99.0 about 1 or 2 years old which has a personal engraving on it. I suppose you would have to factor in if someone wants to have it sent back to have the engraving removed which can be done during service so my guess would be look at the current pricing then factor in a service.
To me a Dornbluth is not like other brands it’s very much a “keep” watch there was a 99.1 on sale recently though.