Let's take a look at the possibilities...
Dr. Jessup - You absolutely need a Dr. Jessup action figure. You'd probably want a normal version of him when he's in the tank and an alternate head for when he first begins to regress physically.
Dr. Jessup Monkey Man - Definitely need a Neanderthal Jessup too.
Full Transformation Jessup - Probably the coolest figure, and really the only one most people would buy.
Mrs. Jessup Full Transformation - She's too boring to get a regular figure. But her inside-out transformation would look wicked on my shelf.
Action Figure Playsets - no action figure line is complete without a few playsets.
Sensory Depravation Tank 1
Sensory Depravation Tank 2
I swear, if I were very wealthy, I would create this line just for fun. I'm sure every kid at Christmas would want a sensory depravation tank to play with.