Low-voltage outdoor lights make for beautiful nights, until a bulb or two or more burn out. Then it's off to the hardware store for replacements. But, before you head for the lawn-and-garden department, first check the automotive section. Why? Both low-voltage outdoor lighting and automobiles have 12-volt electrical systems, and in some instances they use exactly the same type of bulb -- in fact, the identical bulb. So why check the automotive section first? If they have the type of bulb you are looking for, most often it will be substantially less expensiver. Most auto- and low-voltage bulbs are sold in packages of two. And while often identical in every respect from space to overall size and filament, the auto bulbs usually are priced at about $2, while the more costly low-voltage ?specialty? bulbs are $3 and up. Not a huge difference in cost, but as much as a 50-percent difference. And that's your On The House Tip for today.