The situation may be different in the UK, but in the US it's not at all difficult to find galvanized wash tubs. Both Home Depot and Lowes stock them regularly, Atwoods has them, and some smaller hardware shops.

The only difficulty is that they're not big sellers, so you have to prowl around a bit and poke into some of the musty corners to figure out where they keep them. Often even the employees don't know where they are.

But if you're not gonna poke around in the hidden places, it's really no fun goin' to one of those places.

Last time I looked, the biggest they had at HDespot was about $40 (US) but smaller ones - actually more suitable for a tub bass - were as low as around $22 - $25. (A decent broom handle will cost about as much as the tub, if you buy it as a replacement stick. Cheaper to buy a broom and cut the unnecessaries off - if you can find a broom that isn't all flimsy plastic.)

John