Root cellar considerations

I’ve been growing and preserving more food, but storage is a problem. A root cellar is a natural solution, but I was hoping to get more input from those who have used them.

First, I do not have any good hillsides or slopes, so a large, in-ground root cellar would be difficult.

Second, cost is of course a factor. Cheaper is always better.

Are the metal trash can ones preferable to the fridge ones? How do they hold up over time? I would think they would both rot and rust over time?

I would like to store a variety of items—potatoes, winter squash, canned items, etc. Would these work for these trash or fridge root cellars? Mostly I've seen people doing potatoes.

Are the smaller projects worth it? It just seems like a trash can doesn’t hold that much food overall. Is it worth the effort?

Any better ideas or suggestions. I’d love to have a nice beautiful, walk-in one, but I don’t know about either the cost or the practicality without a hill.