Best Public Universities for Major in Economics in US?

Mainly, I am seeking for colleges with low costs and acceptance rate >40%.

Low cost means different things to different people. How much can your parents pay per year? Have you checked your state schools?

“Best” economics also depends on your goals (e.g. pre-PhD (more math = better) or pre-professional (“business” like offerings can be desirable)).

This analysis includes many high-quality public universities:

https://ideas.repec.org/top/top.usecondept.html

If you might be eligible for financial assistance, you can also consider liberal arts colleges:

https://ideas.repec.org/top/top.uslacecon.html