Re: Playboy Mansion Invites
Well, that's one of those counter-intuitive issues that affects most collectibles:
As a rule, anything personally signed tends to be devalued by the personalization of the autograph.
Collectibles that are issued as a series are just that: collectible because they're part of a series. Nagel often personally signed non-collectibles for fans at gallery openings, usually personalizing, dating and signing the piece for them. As such, those pieces (as with all collectibles) carry a more personal value to the recipient than they would on the open market.
It's not uncommon to see non-collectibles marketed as "rare, signed" pieces by Nagel, which actually turn out to be like the ones described above.
Bottom line: If it's signed to you, it's valuable to you. But on the open market, personalization tends to detract from an item's value.