Surefire Sentry pricing for Harman P68

Hi everyone,

New to the forum but recently had a Harman P68 installed in my home and now looking at inverter options for backup. I do have a home generator in place connected to a manual transfer switch but would also like to incorporate the Stove Sentry option for those times when I'm not home to switch over to the generator in time.

Based on what I've read from the SEC site I need the Surefire 512 for the P68 (is this correct?). Does anyone know where the best price to get one is and what that price might be?

Appreciate all your help in advance.

Dealer just ballparked one for me around 350.00