I was browsing through Aerocraft Parts and discovered that finding the right relay/solenoid/contactor can be slightly confusing.  Go to "Electrical\Solenoids and Relays\Solenoids" and you'll find an intermittent duty solenoid suitable for your starter, but no continuous duty devices are shown.  They're under "Electrical\Solenoids and Relays\Relays".  There you'll find a continuous duty relay/solenoid suitable for use as a master relay.  (No reason you can't also use it as an Avionics master.)  So I thought, "Aha! They're classifying an intermittent duty device as a solenoid and a continuous duty device as a relay."  Well, not really.  There is also, under "Electrical\Solenoids and Relays\Relays" an intermittent duty relay.  This device is only $2.50 and looks like its primarily for the landing gear, although the listing says it can be used as a starter relay.  (I think I'll spend the extra $15.50 and get the heavy duty starter relay, or is that solenoid?)

 

Tom Gourley