(MONEY Magazine) – Think, just for a minute, about the amount of money you spend on wine in a year. An impulse buy here and there, a few cases for the holidays, a stash for impromptu get-togethers, special bottles bought and stowed for big anniversaries and birthdays. Whatever you have on hand, and whatever its value, one thing is certain: Wine should get better with age—or at least not get worse. But shove a bottle into one of those lovely but ineffective racks often spotted in kitchen corners, and its value and flavor will tank. Sunlight or even subtle changes in humidity and temperature can turn a nice Valpolicella into vinegar. "The temperature of wine sitting out can fluctuate significantly during the day and between seasons," says Matt Parish, winemaker at California's Turner Road Vineyards. What's a casual wine lover to do?

You don't have to convert your rec room into a climate-controlled cellar. Wine refrigerators are more affordable, offer the same protection and require far less remodeling. They come big and small, relatively inexpensive and very pricey. Just about all address, with varying degrees of success, the four pillars of wine storage: temperature, humidity, light and vibration. "For someone who's serious about storing wine properly, wine refrigerators are a good idea," says Parish. Here's what you need to know if you want your wine to taste the way it's supposed to.

The four pillars TEMPERATURE: The ideal temperature for storing all wines is 55°F, which is 10° to 20° warmer than a standard Frigidaire. "If wine is too cold it doesn't continue to age, and if it's too warm it will age too fast," says Larry Ferguson, sales and marketing director at Marvel Industries, a manufacturer of wine refrigerators. Serving temperatures vary—45°F for sparkling wines, 55°F for whites and 65°F for reds. Storage temperatures, however, should stay consistent.

HUMIDITY: The ideal humidity level is between 60% and 70%. If the air is too moist, the cork can rot. If it's too dry, "the cork tends to shrink, become brittle and shatter, and can cause the wine to spoil," says Ferguson. "You'll see a dry cork start to flake up like rubber on an eraser." High-end fridges maintain optimal humidity levels automatically. Less expensive models simply cool ambient air, usually creating enough natural moisture to keep corks healthy.

LIGHT: You don't have to know Gewürztraminer from Muscat to understand that keeping wine in direct sunlight is not an astute storage method. UV rays are the culprit; they can cause a wine's flavor to turn, a process Parish calls getting "light struck." Keeping wine in a basement or closet solves the UV problem, but if humidity and temperature conditions are haphazard you might as well not have bothered. Look for a fridge with a treated glass door that blocks UV rays.

VIBRATION: The whirring motors on some refrigerators cause motion that can interrupt older wine's aging process, sometimes even loosening corks and causing leakage. To check a refrigerator for vibration, "plug the unit in before you buy," says Han Ko, marketing director for the Wine Enthusiast catalogue. "If it's loud and it vibrates, it's no good."

How and what to buy Smaller units hold around 50 bottles, are about the same size as a dishwasher and cost anywhere from a few hundred to $2,500. Larger models, which can store several hundred bottles, are closer to the size of a conventional fridge and can run into the five figures.

With both sizes, bells and whistles are plentiful—some essential, some superfluous. Digital temperature settings are a must (precise climate control is the main reason for buying a wine fridge). Wooden drawers, instead of wire racks, are also advisable. They tend to roll in and out more smoothly, reducing vibration. Dual temperature zones, on the other hand, aren't worth the extra money they sometimes cost. They do allow you simultaneously to store, say, Riojas at 55°F and Champagnes at 45°F; but you could simply chill your bubbly before serving and save the dough.

We surveyed the specs and mechanics of fridges both from popular brands like Sub-Zero and GE and smaller manufacturers that specialize in wine storage. Danby, an Ontario appliance producer, makes the clear under-100-bottle winner: a 50-bottle unit for $599 (a similar 50-bottle Sub-Zero costs $2,500). It operates at a single, digitally controlled temperature and has seven wooden shelves and a tempered-glass door to block UV rays. If you want to go big, the EuroCave Comfort 260, at $1,999, is a bargain compared with similar models. It can hold 260 bottles, and dual and triple zone units can chill wine to 40°F.

Finally, there is the Vinothèque, ideal for the serious collector or ambitious amateur. Priced between $3,000 and $10,000, Vinothèques are designed for long-term storage. They look like stately antique cabinets, and their moisture-resistant mahogany racks negate mildew. Whether or not you opt for such extravagance, never forget the reason for buying a wine refrigerator: your investment in wine. Between gifts and purchases, a casual collector could easily amass $5,000 worth of wine in 10 years. Just as you wouldn't stuff stock certificates under the mattress, you shouldn't store your bottled wealth anywhere but in a wine fridge. Think of it as a safe-deposit box that coddles the investments within—that is, until you're ready to drink the dividends.