I was a director for the MLG in Newport Beach in the 80's and early 90's. I never sold for investment. These are commercially manufactured prints the artist had no hand in creating other than painting the original (the debate goes on that like Kinkade, he also had elves working on his paintings). Those were Serendipity Gallery prints and currently the Yamagata market is very depressed. I did sell one for a firm I was a consultant for last years entitled "Robbers" which was one of the top images as far as any appreciation for $6,000.00. Those older images always hung around $2,500.00 retail during the heydey of the Yamagata market in the late 80's. They were not at that price big secondary market sellers.
They are marketable possibly at $800.00 to $1200.00 today, framed or unframed (custom framing unfortunately is in the category of used furniture). Their intrinsic value based on what an accredited appraiser would give a writtten appraisal for is likely around $400.00 to $500.00.
One of the best classifieds on the Web is a company I worked with as an art and lighting consultant at their brick-and-mortar gallery in Huntington Beach, CA:
www.artvestgallery.com
Good luck -- the big market is in Japan and that's who "Robbers" sold to. Yamagata left MLG after a long court litigation and produced no more prints in the U.S. except what he did for Disney.