You might try a commercial horticultural supplies company, try googling this.

Thanks, Derekm I'll do that but not tonight. I have been hunting all day and the only thing anywhere near is a rather swish Swedish propogating set up which uses the lid reversed to pop up the modules. Comes with capilliary matting and a hefty price tag and a glowing report but the poly ones did all that and just fitted into wherever you wanted.

Might be reduced to making holes in the plastic trays that fit the pegs.