Good Morning,
It sounds like you are looking for the Hardware Group/Installation Kit only (no brackets) for the GSA28 servo. It is $60 list price.
011-02952-00 - GSA 28 Servo Install Kit, generic without mounting bracket - $60.00
For a complete RV14 servo installation kit from VANS (like the other mentioned, I believe), you would need to get the bill of materials list from VANS to see what they include.
BR,
Brad