Hi Richard and welcome to the Madhouse
I'm with you on the Auto-sleeper, the best conversion in my opinion (I've got one - but not for sale) They are the most numerous, but that's relatively speaking as there aren't vast amounts of Commers out there anyway, so you are more likely to find an AS than any other. But I'm glad to see your not discounting other conversions, but you need to act quick when you see one - and be prepared to travel.