I never discount my work. I provide a fair price. What I will do in order to close a deal is offer a different incentive - perhaps a free 30 min photo session, or a coupon with an expiration date for same that they can use or pass along to someone else.

When you go to a restaurant, do you get a quantity discount on the meals if you bring more guests? When you use a caterer for a large event, do you get a discount based on the number of people? Hardly. You might get coffee, an after dinner drink, maybe a dessert comp'd, but there is no benefit to lowering your price.

The rationale behind the coupon is to increase business using a promotional consideration, and it works beautifully.