DoL already has a process for determining prevailing wage for a given location. There is no reason why "sorting by wage" can't mean "sorting by ratio of wage to local prevailing wage".
You must file an amended H-1B petition if your H-1B
employee changed or is going to change his or her place of
employment to a worksite location outside of the
metropolitan statistical area (MSA) or an “area of intended
employment” (as defined at 20 CFR 655.715) covered by the
existing approved H-1B petition