DestinationCoupons offers a Madame Tussauds Adult Ticket in San Francisco, CA, for $13 via this printable coupon. (Select "Click here for your Coupon" to see the coupon.) That's $9 less than purchasing directly and the lowest price we could find. Some restrictions apply. Book this travel deal by April 30.
Of note, you can also get a Children's Ticket for $10 via the above printable coupon. That's another savings of $6.