When Katie Echeverry first started to sell vintage clothing, she heard one thing repeatedly: "I love that dress. Do you have it in my size?"

She laughs because the very essence of vintage is that it's one of a kind. And therein lies the problem for retailers.

"The sizing was awful and I was lucky if I found a great size 6. Forget an 8 or a 10," Ms. Echeverry says.

What started as a hobby mushroomed when her Web site was mentioned in Glamour magazine. "We had our best month ever," she recalls.

Realizing the potential, Ms. Echeverry decided to switch from vintage to vintage-inspired clothing and began to research designers who specialized in reproductions.

"I found a lot of beautiful things that were very expensive. But the majority of people can't afford to spend $400 or $500 on a dress and I wouldn't myself. I took a leap of faith and poured my heart and soul into the Web site. Within a year I hired my first employee and now I have seven," says Ms. Echeverry, 36, a former pharmaceutical rep.

With price very much a factor, she started unique-vintage.com from her home base in Burbank, Calif. Many of the fashions are less than $100, with some closer to $50. Pick an era and there's a great selection -- in sizes from XS to 2X. Ms. Echeverry buys from different manufacturers but also designs some of the dresses herself, updating vintage by changing the colors or adding sleeves.

Who are her biggest customers? You'd be surprised.

"We have a lot of ladies in their 40s or 50s who love '40s or '50s style, cinched waists, swing dresses, very ladylike."

Ms. Echeverry quickly discovered there is far greater demand for vintage dressing than she could have predicted. She does substantial business in theme weddings and galas, with flapper dresses being especially popular. Movies and TV shows such as "Mad Men" can increase sales by the decade, and women who want a cocktail dress they won't see on anyone else frequent the Web site, as do young girls looking for prom dresses. They also can find a range of period-perfect accessories to match, along with aprons, shoes and bathing suits.

"I think that women and girls want to dress in a unique fashion. People are tired of everyone wearing the same thing. This is a nice way to be different and stand out from the crowd without dressing in a revealing fashion. Some of the moms have thanked us for offering cute clothes at affordable prices that are not too revealing."

One of the busiest seasons is right now, a few weeks before Halloween. Costume rental stores can charge an average of $100 or more for that flapper dress or '40s frock. At unique-vintage.com, customers usually pay less, find the right size and get to keep it.

"We try to specialize in dresses that can be worn for a costume or theme event, but also can be worn afterward," says Ms. Echeverry. Unlike, say, bridesmaids dresses (they sell those, too!).

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