I have three left, one green one sold, of various poly drums of different sizes / types which have been cleaned, sterilized, and have been used to store emergency water in a basement for some years. All have been cleaned and de-smelled thoroughly for this use, with lightly chlorinated water changed annually. Just emptied them this weekend to open up the space, and the water was as fresh as when I refilled in June.
Bung spouts (unused) for the green drums are included with those items.
Going rate on these varies by type, but in general I think $30 a piece fair. Buy all four, they're yours for $75.