How about a 10g glass tank?
he is probably looking for the white storage containers that tropiquarium use to sell. I know that ACC sent out a blast recently with a new shipment in if you can't find used ones.
I'm with Sunny. I been using 5gal buckets from Lowe's (the blue ones) for about 3 years now with no issues. I use one as my dirty bucket (what I empty water into from my tank) then I use others to hold RODI water and Saltwater mix .I have not had one bucket tip me. The only issue is one of the bucket the white handle crack but still useable