my humble attempt

The novel has three parts: The Talisman, The Woman without a Heart, and Agony. The novel opens with the main character, Raphael de Valentin, losing his last gold coin at the roulette table. Before he commits suicide by throwing himself into the Seine, he enters an antique shop full of bizarre remnants from different ages and civilizations. The strange owner of the shop directs him to a mysterious piece of animal skin that King Solomon supposedly cast a spell over eons ago. The skin is capable of granting any wish the holder makes. The only catch is that with every wish the skin shrinks and when the skin has shrunk to nothing the holder will die.

The first first thing Raphael wishes for is a wild party to snap himself out of his depression. Immediately, as he leaves the shop he bumps into several friends of his heading to a banquet thrown by a banker who's starting a new opposition newspaper. His luck picking up, Raphael is offered the job of editor for the newspaper. The picture of dissipation and chaos that Balzac paints at the end of this party is quite incredible.

This one seems to be closer to what Mark said. You can put it either "Every time they paid with their vanishing freedom for their wishes satisfied" or "Their freedom was vanishing as their wishes were satisfied one by one", etc.

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Note added at 2 hrs (2007-02-03 16:24:09 GMT)
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Unfortunately I could not find anything related to "skin".

Like "шагреневая кожа"

I personally would omit any reference to "Shagrenev skin "at all
and only preserve the meaning of the whole sentence.
Say, "they saw their freedoms vanishing in thin air " .
However, if you desire to preserve the original , you could always
use a little clarification "...shrinking, like Shagrenev skin in Balzak`s novell". Obviously, meant for a well-read audience:)


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Note added at 4 hrs (2007-02-03 18:47:34 GMT)
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"vanishinf FAST in thin air" rather

some alternatives.

HTH
Sara

***Мой вариант:

Their freedom has being shrunk like a piece of magic shagreen which
did so with an every fulfilled owner's wish.

Скажу честно, что я "освежила" свои познания в области творчества О.Бальзака и пришла к выводам, которыми хочу поделиться.

Мне кажется, что самой фразы маловато, чтобы выполнить хороший перевод. Дело в том, что неясно - кто они, почему стали терять свободу и что автор понимает под словом "свобода" (физическая, творческая, экономическая, пр.).
Ведь в романе шагреневая кожа не просто съеживалась/уменьшалась, а 1/ это происходило медленно;
2/ и главное (для меня) - в обмен на исполнение желаний владельца: таково было условие с самого начала.

http://www.lib.ru/INOOLD/BALZAK/shagren.txt
*Обладая мною, ты будешь обладать всем, но жизнь твоя будет принадлежать мне. Так угодно богу. Желай -- и желания твои будут исполнены. Но соразмеряй свои желания со своей жизнью. Она -- здесь. При каждом желании я буду убывать, как твои дни.*

Для меня это выражение известной философии :
за все нужно платить, причем чаще всего цена весьма высока.

Если в данном (предложенном нам ) отрывке автор подразумевает, что ххххх теряли свободу (права?) В ОБМЕН на какие-то льготы/исполнение желаний, то это происходило медленно - но процесс был предсказуемым, исходя из аналогии.

Оказывается, само название просто приобрело "нарицательный" смысл в связи с одноименным романом. А вообще слово "шагрень" существует и в русском, и в английском языках, означая кожу определенного типа (шероховатую, как правило).

http://dic.academic.ru/dic.nsf/muller/NT000F952E
shagreen noun шагрень
http://dic.academic.ru/dic.nsf/ushakov/NT0010A14E
ШАГРЕНЬ, шагрени, мн. нет, ж. (фр. chagrin с араб.). Мягкая шероховатая кожа (козлиная, баранья, конская и т. д.) с рисунком, напоминающим натуральный рисунок козлиной кожи. Портфель из шагрени.

"The Picture of Dorian Gray" is a novel by Oscar Wilde, and it is much better known in the West than Honore de Balsac's writings. By using this analogy, I believe you may have a better chance to connect with your audience. Here is a short recap, courtesy of wikipedia, where a much lengthy recap also may be found.

The novel tells of a young man named Dorian Gray, the subject of a painting by artist Basil Hallward. Dorian is convinced, through a series of encounters, that beauty is the only thing worth pursuing, and because his newly painted portrait reflects his beauty, he cries out, wishing that the portrait Basil has painted of him would age rather than himself. Dorian's wish is fulfilled, subsequently plunging him into a sequence of debauched acts. The portrait serves as a reminder of the effect each act has upon his soul, each sin being displayed as a new sign of ageing on the portrait.

The Picture of Dorian Gray is considered one of the last works of classic gothic horror fiction with a strong Faustian theme... In modern times, the book has been referred to as "one of the modern classics of Western literature.



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Note added at 2 days7 hrs (2007-02-05 21:20:08 GMT)
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"slipping away" instead of "disappearing" may be better at containing the allegory.

A fairytale twist.. :)

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Note added at 9 hrs (2007-02-03 23:51:40 GMT)
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More thoughts:

Their freedom was slipping away like a wish upon a falling star.

or

Their freedom was dying like the last embers of a fading campfire.


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Note added at 2 days8 hrs (2007-02-05 22:59:46 GMT)
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Another thought, the Great Gatsby is on many American high school reading lists... http://www.vocabulary.com/VUctgreatG.html
So another possibility for something that would probably be recognized by more people:

Fading like Gatsby's facade.