Oddly this was in the seasonal Isle rather than with the garden stuff on the foyer but here it is:
A slimline 100L water butt including stand, tap and diverter £19 in store @ morrisons
The second cheapest price is b&m bargains at £20 but only at their garden centres and they didn't have any last time I was there.
Most shops are selling these for about £20 without the stand.
I saw this in Peverell store in Plymouth,which is not their biggest store in Plymouth,so a good chance most stores will have one.
cue all the butt jokes...