I’m going to be applying to music schools for french horn this fall. Does anyone know what top state schools that give music majors in state tuition. I know UNT does but I’m looking for a few more. I need to stay around $20,000 or less so conservatories are out for me.
Read the subject line and jumped in here to suggest UNT 
I’m also going to be applying to UNT. If your stats are good also check out U of Kansas and Florida State University. U of Utah is a lower-level music program (as far as I can tell) and off my list, but they are very generous with OOS aid.
If you are admitted as a music major at FSU after auditioning, you typically receive in state tuition.
My D just went through this whole process for the French horn this last year. My D was very concerned with the teacher…and wanted a conservatory… however many private colleges will give big scholarships which offset the price. I suggest looking at Loyola NO which is very generous and the coach Mollie Pate is amazing. SDSU(San Diego State) has Mike Mc Coy who is also AMAZING. He has been my D’s teacher for 6 years and is a seasoned professional. Feel free to Pm me with any questions
Look at University of Arizona, Arizona State and University of New Mexico. Indiana University gives good money if you can play and your grades/scores are solid.
New York’s SUNY system is relatively affordable. We liked Purchase. Some on this forum have mentioned Crane at Potsdam too.
Are you eligible for any financial aid?
I assume you are using the term “conservatory” to mean free-standing conservatories. BM programs at schools of music at universities are essentially conservatory programs.
There may also be conservatories/schools of music on campuses of colleges or universities that might give some financial or merit aid.
State schools can be a great way to go, but just be careful not to limit options that may actually be possible for you.