The Circuit Cellar Inc. has advertisers with just what you need. They also have articles and related schematics. You will need to know if you have line of sight or interference issues. Otherwise, it is best to license or rent a system. Bandwidth is expensive. nbucska questions are critical. You need to have clear systems requirements before investigating costs or alternatives. Requirements are "what" you need to do. You mentioned needing UHF VHF with 3 frequencies. That is "How" you do something. That is anathema to good systems engineering.