Some people prize fountain pens because they embody an ethos of individuality in an increasingly mass-produced world. ''They are high-touch items,'' said Marie Picon, editorial director of Pen World International, an 18-year-old magazine devoted to fountain pens. She compared fountain pens to old-fashioned, nondigital watches. The pens ''are thought of as an antidote to high tech,'' she said.

Moreover, not all fountain pens cost as much as a down payment on a new car. Pens that sell for as little as $30 may perform just as well.

When shopping at either end of the spectrum, some general rules apply. Assuming that the pen is for writing, not display, shopping for a new or vintage pen should be based on characteristics like length, thickness, weight, the size and material of the nib and the way the pen feels in the hand.

''Don't buy a brand just because it's prestigious or pocket jewelry,'' said Richard Binder, a pen restorer in Nashua, N.H., whose skill at customizing nibs has transformed his name into a verb in the pen world: aficionados brag that their pens have been Binderized.

Ms. Picon says pen shoppers should ''never buy a fountain pen without writing with it.''

Most sellers let prospective buyers dip the nib in ink before testing, though a pen's true performance can be gauged only by filling the barrel with ink. Shoppers should buy only from reputable dealers who are willing to replace products if they are defective. One of the most respected shops, pen lovers say, is the Fountain Pen Hospital in Lower Manhattan, which has been in business since 1946.

No matter why they are bought, fountain pens incite intense passions, even though they account for less than 2 percent of the $2.3 billion annual trade in writing implements, which also include ballpoints, roller pens, markers and pencils, according to the most recent statistics from the Writing Instrument Manufacturers Association.

But an interest in fountain pens can quickly become an insatiable thirst. The Fountain Pen Hospital says it receives weekly calls from pen lovers on the prowl for the latest model. ''It's a habit for some people,'' said Terry Wiederlight, the store's president.