This OEM Jaguar thermostat is a direct replacement for the V8 Vantage at a much lower price than you'll find at an Aston Martin dealership. You can buy the thermostat on its own, or include the thermostat housing seal (it's a good idea to replace the seal and I highly recommend opting for the seal).
The thermostat housing seal is an OEM Aston Martin part.
Redpants offers the V12 thermostat on its own, or along with the o-ring and seal (the “V12 Thermostat Package”). The thermostat, o-ring, and seal are all OEM Aston Martin parts and fit V12 engines including the DB7 Vantage, gen-1 Vanquish, DB9, DBS, Rapide, V12 Vantage, and Virage.