Haven't gone yet, but I don't think you need to worry. Your ftp confirmation should list the print as one of the items, so in a pinch (and it's unlikely you'll be asked), you can show your confirmation to prove it's a gift. As for value, the strategies board lists it's sale value as $200. I doubt they'll be that concerned, but if you're really worried, I'm sure Guest Services could give you some kind of statement of value. Mostly when they do an audit, it's not to calculate what you've got to the penny, it's to make sure you're not bringing in $1000's of dollars extra worth of stuff.
Some people have been having them shipped home. That might be a solution, if you're really uncomforatable with it or it won't fit in your luggage. This can usually be arranged from your resort gift shop.
Ciao,
Mort.