... a PDF exported that contains all of our card designs, laid out the way we want...

Not sure exactly what you mean by ``card designs'', but if it's just text, a very simple way to do it that I'd try would be to pull the data out, then (possibly using HTML::Template) drop it into a Plain TeX file and process that file with pdftex returning the pdf to the user.

I haven't yet looked into how to get graphics in, but TeX is great for making beautiful pdf's.