Downloadable goods or real, postable ones?....virtual is fine because you can get away with no SSL...just take an email address and send 'em to paypal.
Real goods you want SSL because you need to collect an address and maybe other details. So you need: IP addy for the site & SSL cert. You can use a shared certificate, but it doesn't look very trustable & may put people off.
Depending upon the complexity/facilities you need in your cart, I'd recommend either of the following freebies:
Simple, easy to install, but has limits in what you can do with it:
http://www.maianscriptworld.co.uk/f...t/free-paypal-shopping-cart-system/index.html
Much harder work, but has pretty well everything you'll need:
http://www.zen-cart.com/
Just starting out, I'd go with the first one to start with. You can always install both in different directories, and flick from one to the other with a meta-refresh when you have got the hang of Zen Cart (if you need it). The learning curve is reasonable and step-by-step with the Maian Cart, but Zen assumes quite a high degree of competence & you could be weeks learning from scratch. And that's one of the easy ones.