Vacation time pile up faster than vacation money these days. But if you plan ahead, you can get your vacations at bargain prices. I know, having returned from a half-price ski trip (Sidewell Friends School auciton last spring) complete with one-third off for ski lifts, rentals andlessons (Alexandria Y auction, December). The big vacation auction of the season is next Friday, a benefit for six charities and scholarships sponsored by the Junior Women's Club of Rockville. They have been doing vacation auctions for thirteen years and have worked up this year's list to cover ninety vacations worth a total of $15,000. If last year's auction is a guide, the vacations should sell for about two-thirds of their value. You can get the list ahead of time, check with the travel agents or guide books for their actual value and set your top bid. Youwill have a choice from twenty-two states, seveal Caribbean islands, Canada and Mexico. You can buy a week for two on an Arizona tennis ranch or a weekend in Williamsburg. The Waikikian Hotel in Honolulu has offered a week for two, New Orleans's Royal Orleans a weekend. Be sure to carefully not the the possible dates, the number of night and guests and whether meals are included. Then book your air fare (which is not included) at least forty-five days in advance to save another chunk of money. And send me a postcard.

Vacation Auction, Jr. Women's Club of Rockville Holiday Inn, 8120 Wisconsin Ave., Bethesda. Friday, March 4. Cash bar at 7 p.m., auction starts 8 p.m. $1.50 donation. For catalog, call 296-3025, 8:30 a.m. to 2 p.m.