At participating Subway restaurant locations, buy a 30-oz. drink and get a 6" sub sandwich for free when you sign up for weekly text offers. That's a savings of around $4 and tied with our mention from last July as one of the best deals we've seen for a 6" sub from Subway. (A 30-oz. drink costs around $2, depending on location.) Some exclusions may apply. Click here to find a location near you.