Taiwan and South Korea also have new designs. Those might be more affordable.
The reason I suggest this is simply due to development time. Building a licensed copy of an existing design would greatly speed up the time from laying the keel to launch. The Littoral Combat ships have not proved to be up to the job. It was a good idea that didn’t work out.
I understand where you’re coming from. The design wouldn’t take a long time if the USN could write a simple specfication and put it out there to the shipbuilders. If they take a proven hull & engineering, you cut out all the modeling and testing. Remove the Aegis system, put in a point-defense AA system and retain the Sonar Suite. There’s your interim design. Start building this year.
They you build a cheaper design on a new hull. Single screw, gas turbine. Or you take the Coast Guard’s new endurance cutter and muscle it up a bit.