When looking for a Christmas tree this year, an old consumer maxim -- shop around -- is especially good to remember.

An informal survey of the Washington area found that the price of a six-foot Scotch pine, the most popular and least expensive tree, can vary by as much as $18 -- from $15 to $33 -- depending on the seller. According to the survey, however, prices do not differ greatly among the Maryland and Virginia suburbs and the District.

And wherever you shop, expect to pay more than last year: Prices have gone up about 10 percent, the survey found.

Tree lots operated by civic and church groups, such as Boy Scouts, Lions clubs and fire departments, generally have lower-priced trees than commercial lots, but often they offer less variety.

Earl Grimm sells a 10-foot Douglas fir for $48 at a lot on Sudley Road in Manassas. In Rockville next to Congressional Plaza, Mark Willcher sells the same tree for $50.

Another a major factor in a tree's cost is how long it took to grow. "A six-foot Scotch pine takes six or seven years to grow, and a six-foot Douglas fir takes 12 or 13 years to grow," explained Won Yi, who sells Christmas trees in Woodbridge. Six-foot Douglas fir trees can be found at area lots from $25 to $40, depending on fullness and shape.

The top-of-the-line trees are the Fraser and Douglas firs and the Canadian balsam, according to Helmut Jaehnigen of The Behnke Nurseries Co. in Beltsville. He said the Douglas is favored for its orangy, piny aroma. The two firs have begun to sell as well as the low-priced Scotch pine, dealers said.

Dealers said trees vary in longevity as much as they do in price. The Scotch pine does not retain its prickly needles as long as the Fraser or Douglas firs, but it lasts longer than a blue spruce. White pines have the longest needles, followed by Scotch pines and Fraser firs.

The most expensive tree -- a 13 1/2-foot Douglas or Fraser fir for $250 -- was found at Sundback's on Wisconsin Avenue in Chevy Chase. The massive trees are all sold out, many bought by area corporations.

But many trees are still left for the taking. Dealers said their best selling days began this weekend.

Some tree dealers attribute slow sales in the early part of December to unseasonably warm weather. "It's hard to stay in the Christmas spirit when you're wearing a T-shirt," said Lt. Kenneth Burchell of the Bethesda-Chevy Chase Rescue Squad, which operates a lot.