I am considering using a promotion I saw back in the early 90s. You purchased an 8-ounce coffee mug from a big 24-hour burger chain in Texas (Whataburger) that also sold breakfast and whenever you brought it back you could fill it for a nickle. I am considering a 14-16 ounce travel mug for a quarter. Of course, the idea is that if they come back to fill the mug they will (usually) figure “I got my coffee cheap, I guess I could spend $1.50 on a sausage biscuit or $2.50 on a breakfast burrito”.