Costco and Big Y are at the top of the list. If you’re in the Danbury area Caraluzzi’s is also very good

Plates DO NOT have to go back to the DMV anymore. Save yourself the headache and cancel your registration online. The DMV should automatically notify the tax assessor in your town that the registration has been cancelled but print out and save the cancelled registration receipt just in case. If you want to transfer your plates to a new car select “held by customer” when the website asks for the plate disposition. If you select “cancelled” or “lost/stolen” at that prompt I’m pretty sure the plates can’t be transferred.