Hello all..
I have a steady supply of 25L (plus about 5L headspace) food-grade plastic containers. They were formerly used to store pure Ethanol and my mother can get them from her workplace. They have a 2" screwcap with a rubber o-ring that forms a very tight seal. They're pretty robust (I haven't had any explode on me yet while priming)and the cap can be drilled into to take a bung & airlock.
If anyone wants one or two of these, they're free if you happen to find yourself in North Cork.