Cheap Fish Tanks

We moved this past summer and inherited a small pond and a goldfish. Now that winter is getting closer, I need to bring the fish inside as the pond is too shallow for it to spend the winter.

Given the size of the fish, I feel like I would need at least a 30 gallon tank. Plus I think there are a few more fish in the pond (not sure the breed). I was looking at options for new or used tanks and they are quite pricey.

I think the previous owners overwintered the fish in a Rubbermaid tote, and I think I will do the same.

I am concerned with the leaching from the plastic, but given that the pond has a liner, I feel like it might be similar.

Are there any other concerns with using plastic totes as a fish tank? Any people with experience?

Rubbermaid stock tanks are used to raise ornamental fish at some commercial farms.
When we started our farm, we used Rubbermaid 32 gallon garbage cans. They worked great.

I also had a seasonal pond with koi and goldfish that I had to bring indoors. What worked extremely well was a kiddie pool. Great value for the volume and they're meant virtually purpose built. I did have the odd fish jump out so I covered it with net. It afforded a nice view too.
I recall the rule of thumb for goldfish is 1 gallon per inch of fish.