经济成本低怎么说英语

"Low economic cost" is a good way to express this concept in Engpsh. You could also say "cost-effective" or "inexpensive" if you want to convey the idea that the economic cost of something is low relative to the benefits it provides.

For example, you could say "This manufacturing process has a low economic cost because it uses fewer resources and generates less waste than other methods." or "Investing in energy-efficient apppances is cost-effective because it can save money on energy bills in the long run."