Lee@emctiles
TF
I think the lash clips would be really good for large uncalibrated slate or something. the curved base would be able to sort the different thicknesses.
A reasonably local tile shop I use stock Siri smart level clips and wedges and I find them great - used 500 yesterday and only had 2 break on me and that was probably my fault.
Can't remember how much the wedges were as I've not needed to buy any more for a long time but I just got 1500 clips for £90
FYI The Siri Smart levelling clips are now available in 1,2 and 3 mm Nick @macten along with a 2mm for 20mm tiles.