I built a 40 gallon system and it is no where near large enough for what I want to do.

I would go with at least a 150 gallons. Try the rubbermaid stock tanks. They are a decent price and you can get them anywhere.

10 gallons may be ok for Fry but I would not want to try and grow out any quantity of fish. I also do not like feeder fish because they are notorious carriers of various diseases. I would buy a small pet store fish that is not a feeder. Pladids or something.

Go bigger.