An unofficial run down of what is out there:
Aerobat (PS Composites has a mold I think)
Edge (both pre-date Acrobat and can be fun, but not typically mystery able)(PS Composites has a mold.. not sure it matches my Edge though...)
Acrobat (standard cut) (PS Composites has the mold)
Acrobat (master cut - lots of fun, endless cartwheels, depending on cut and body shape it can be mysteried, but really too much volume for most folks)(PS Composites)
Oxygen (12 or so built... corran addison's design. Amusing to paddle, but turns class II in to IV (and for some folks flat water in to V

)(PS Composites)
Meltdown (UK boat... not sure if any on this side of the pond. One of these days!)(Valley in the UK had it... not sure now?)
Maven... not a great design, but a good test of your paddling ability

. Mysteryable by someone... maybe. CAN be a lot of fun though (I still take mine out sometimes:) ). Kind of like paddling a scalpel. (I have the mold)
Mentor - the boat that got the most mysteries at the past few squirt events. 2 in existence. More can be made...(I have the mold)
Ceam Weaver - Jim Snyder's C1 squirt design. I believe only the prototype / first boat exists, but there is a mold. Contact Jimi for more info (I believe he can make a boat, or have PS Composites make one... Jim has the mold)
Note: The Maven and Mentor are both my designs, and I have both molds. I don't really have time to build boats right now, BUT have a local shop who builds ultralight canoes with lots of experience that watched the progress of both boats that are willing to build a boat if there is interest. Price dependent on layup.
If you are ever in upstate NY I have the follow on hand, and am right on the river if you or any one else wants to try them out (I'm only listing the squirt boats... there are others...):
Edge
Acrobat (standard cut)
Acrobat (master cut)
Oxygen
Maven
Mentor
And if anyone has an aerobat for sale... I'd really like to finish off the collection at some point! Likewise I need to try and get a Meltdown. One of these days.
Oh, and under the "Boats" section you can find images of most of these. Yes we need to upgrade image quality now that everyone is on broad band...