Yea, I have that issue too. I suppose it's a region lock as I didn't have that problem when I went to Paris. Bought a few apps over there. However, when I came back to PR, the problem returned. I've emailed Google Market support about it a few times and they don't answer.
Since Honeycomb is Android 3.x I'm actually worried they don't fix this and by 4.x there will be no way to get paid apps in my region...
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