Yes I agree and this company is the one http://www.containerwise.co.uk/propagation-trays-600-400.html and the trays last up to 15 years. But you have to buy a lot! (a pallet-load)
Also their smallest tray has 84 cells I think, most have126 cells or more. I have written to ask if they might make a smaller, equally strong tray for gardeners.