I used an RM-9 with my TVC and it worked fine. The gain is adjusable on it via a toggle switch on the top plate. I now use a TRL D-225, but that is not in your budget. Some amp specs to look for are an high input sensitivity (under 1V is preferable but you may be able to get away with 1.2V) and an input impedance of at least 50k ohms.
