Start by talking to your parents about what they will contribute.
Then run the net price calculator on each college of interest to see if it will be affordable on need-based financial aid. If a college is not, then check if merit scholarships will make it affordable. If you need scholarships (merit or ROTC) to afford the college, then the reach/match/safety assessment must be made on the scholarship, not admission.
Do not write off your in-state public universities so quickly, because they may include some more affordable options.
If you want to be a military officer, consider also the academies of the branch(es) of interest.