Short circuit your competitors’ promotions by sending out a marketing piece hyping some features your products have that the competitors' don’t.
You should absolutely have the email address of all your customers in a database. If not, you’re missing a real marketing opportunity. You hear that your competitor has a promo on impact sets and screwdriver sets this month. Using Constant Contact or some other email service, send all your customers a marketing piece on your similar products, hyping some features your products have that the competitors don’t.