Something of a guess, but I think this is what your text is getting at (given the context of how PRA is used here). Marketing texts often borrow English abbreviations.
I think this is new(ish) way of discussing what is traditionally called the target audience. See p4 of link provided.

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Note added at 1 hr (2011-09-05 12:47:42 GMT)
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Yes, Tony M's note is quite right to draw attention to the use of 'des'. If this is correct (my experience of working with marketing texts is that they are often hastily written and full of typos) then my suggestion (guess) is probably incorrect.

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Note added at 2 hrs (2011-09-05 13:56:35 GMT)
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Mind you, how can the text be talking about the Purchasing Decision Maker? It seems to be talking about target customers for the stores loyalty card. The Purchasing Decision Maker is a member of staff. So I don't think this common meaning of PRA applies here.

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Note added at 4 hrs (2011-09-05 15:37:22 GMT)
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Actually, I agree with the first answer myself now! I was not familiar with the usage of PRA outside of a company context. Here is another link, which wraps everything up nicely.
http://www.office-elevage.fr/consommation/csa/Enq_qti_dom.pd...