No ready made plywood door on sale for bathroom size, and they don't last and hard to maintain. Cheapest is PVC folding door as shown above by other forumer, the price is RM90+- w/o installation.

Or order a PVC swing door from hardware shop, last year they quoted me RM 150 for one w/o installation.

I prefer PVC swing door than the folding one, as the track mechanism of folding door don't really look promising to me. I'm comparing those RM 90+ fold door and 150+ swing door of course, not sure of those higher price folding door with the better track mechanism.