(Or how Piemur got nine pies for a 32nd!)
There's been much argument over the value of the Pernese mark. For references other than the ones given in this thread, please read Dragonsinger, DLtP, or Dragondrums.
With the mark system being as complex as it is; being set up in fractions rather than a base number, it is difficult to note what an exchange would be between the Pernese Mark and the American dollar; let alone the euro or pound. Most of these are guestimates--the mark has been arguably different in value depending on those who read the books. A whole mark has been said to be at thirty, twenty, and ten dollar values. For simplicity's sake (and for my failure at math), we'll round off nicely and keep with the lowest values given.
Remember that marks are wooden coins (sometimes described as square, others circular) that vary in value depending where they came from. Benden's marks are reputed (from the books) as being the best, while Farmer's marks are only accepted in certain places.
1 (whole) mark - $10
1/2 mark - $5
1/4 - $2.50
1/16 - $1.25
1/32 - $0.63
And so on.
More reading on this subject can be done here -
http://www.newsfrombree.co.uk/pies.htmhttp://www.dragonridersclub.com/drmain/drpka.html 
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