Since Wendy’s launched its ninety-nine cent menu in 1989, consumer demand has led to value menus in many fast-food chains, and in this economic climate dollar menus are especially popular.

Rising food costs, however, have shrunk the already small margins on dollar deals. At the same time, cash-strapped customers are less likely to buy the full-ticket items on the menu.

Enter the TWO-dollar menu. What one consumer psychologist calls a “magical price point” has appeared on the menus of KFC, Taco Bell, and, most recently, Subway, USA Today reported. Taco Bell’s take on the two-dollar deal included chips and a drink, and Subway’s two-dollar sandwich is also marketed as a full meal, making the items on McDonald’s dollar menu look like snacks by contrast.

The two-dollar menu might be catching on quickly, but its effect will vary. Restaurant chains have to find out how to make it lead to steady profit. All restaurants should have robust answers to the following questions before getting in the $2 game:

• What items can retain a viable profit margin at $2?
• How will your current value offers (like Subway’s $5 foot-long) fare under the pressure of a better deal?
• How can the $2 deal be leveraged to sell pricier add-ons?
• Could the $2 deal be paired with aggressive marketing of seasonal specials?
• How will different franchises respond to a nationwide $2 deal?

Controlled testing is the smartest way to introduce this buzzing price point.