My comebacks for various salespeople:
Door-to-door magazine sales: I get my magazines at the library.
Door-to-door carpet cleaners: I have wood floors. My furniture is leather.
Other in-person solicitors: I only give by mail or my husband has the checkbook.
and my newly developed favorite for the kiosk-based lotion dispensing freaks at the mall:
I'm self-lubricating, thanks.