foam boards

im finding reclaimed 1.2 m x 2.4 m x 100mm insulation boards online for £29. it's too expensive. Does anyone know a supplier or an equivalent technology to kingspan that is less. Has anyone tried blowing their own closed cell (waterproof) foam and do you know where I could get it. still...

Looking at options for tiling a bathroom 2.3M(L) * 1.7M(W) * 3M(H) For the floor looking at replacing old uneven boards with 25mm marine ply (and sealing). I think the walls already have tile-on-tile, so going to take them back to what I'm sure will be pretty rough/uneven brickwork. Was going...