Billet Specialties Thermostat Housing?

I moved to the billet specialties housing and haven't had a leak or issue since. When I needed to change out the thermostat I wanted to change the o-ring just to be on the safe side. Summit wanted damn near the price of a housing just for the o-ring! Went to McMasterCarr and found the right size o-ring and spent less for 25 (smallest quantity I could buy) than the price summit wanted for 1 Billet Specialites o-ring.