I created a (very) simple web store for my wife, with PayPal
http://www.direct2usales.com
As far as I know, there is no way to pass dynamic data to
PayPal
Everything I pass to the PayPal shopping cart is hard wired
in the code for each "add to cart" command on the site... based on
the example code I downloaded when developing the store site
For anything else, if it is even possible, you might browse
around at the PayPal developer site to see if they say anything
about passing dynamic data to their shopping cart... I never saw
anything like that, but it's been awhile since I got her store code
working, so PayPal could have added new options since the last time
I looked