Hm, just went and asked my husband, and we got those two brown rain barrels off Woot! But he says he's seen them available elsewhere - try Amazon first.
Not sure but these might be the ones - they're available in other colors, too.
https://www.amazon.com/dp/B0033VJ04K/
I also have two of this type, but they're dark green, 75gal capacity but much more expensive.
https://www.amazon.com/dp/B0033VJ04K/