I use the Discovery SF600 which has never failed me. Its about 800 KES in Luthulianyone who can advice on a good finder...
check it out if you are in Nairobi Area. It does S/S2 scanning and you can have it beep on signal. You can also edit transponder frequencies on it and the battery can give you about 3 hours non stop use which is more than you need if you know the game.