When DS was transitioning from peg to jigsaw puzzles the earliest jigsaws he did were 2 piece ones. One was similar to this set:
http://www.amazon.com/Infantino-156-034-My-First-Puzzles/dp/B0006N8YFO/ref=pd_sim_ba_4Several friends have this one on their fridge, conceptually similar to a jigsaw:
http://www.amazon.com/LeapFrog-Frid...mp;ie=UTF8&qid=1315798071&sr=1-1We also had some expensive 3D wood puzzles with just a few pieces that DS had a lot of trouble with due to hand eye coordination, holding the pieces at the right orientation and height and then sliding them down to connect was a challenge, moreso than a flat puzzle. By the time he grew to where his fingers could actually manipulate to do it he was bored with the number of pieces.
Haba makes a few flat style puzzles similar to the 70s types:
http://www.maukilo.com/paulina-discovery-puzzle.html DS initially found ones with bumps on each piece easier to do than ones that have flat smooth edges. Because with bumps and spots for the bumps to fit it is clearer how the pieces line up.
We gradually accumulated some good puzzles from places like ebay and yard sales. Once DS could do 8 or 12 piece jigsaws there were so many more to choose from.
Good luck with the search.
Polly