Know how much that is? I'm sure I could make something that does the same (and have that does similar using magnetic thingies that you get on wardrope doors) for a few quid.
Make your own with ply and magnetic thingies. Tile the ply and stick magnetic thingies on the back in the corners, and use 4 noggings at 45 degrees in the corners in the wall. You have to chisel out the deapth of BOTH the magnetic things in the noggins and ensure they slot in (you can chisel out say 10mm more around where the magnetic things will be screwed onto the wood to ensure it will fit) and bobs your uncle. Would cost the cost of 4 magnetic things and a couple of ft of 2x1, if that.
used very similar access panels in germany 16 years ago, over there the tiler has to build the bath panel out of 50mm thermalite breeze blocks and install a frame access panel similar to the one shown probably not done like this now with all the foam backer boards available these days