Okay, I bought from the mysterious chinese maker and they turned up really fast. They aren't shorts, though, instead they're full-length trousers! They seem to be made quite well, actually, and inflate nicely. The only niggle is the non-Schrader valve - it seems to be a Dunlop or Woods valve, so I've had to bodge an adapter.
I quite like them, actually. Wore them for a few hours the night I got them - inflated, of course! I'm going to try sleeping in them tonight. There's a zip through the crotch, so I can theoretically use the bathroom with them on. Or play some other sorts of games.

I've decided I'm not going to try everything at once...
Sei.
Embrace your inner wierdo! No-one else will! (No, they'd be more likely to lock it up and throw away the key...)