Help with a shopping cart solution please

Using WPMU 2.8.4.
I’m looking for a shopping cart solution for my web design business. We sell digital services, so no shipping or anything…
Here’s what I’m looking for:

– Customers select a package (theme, features, addons) and add to cart.
– Customers pay via paypal, google checkout, or FirstData(?)..
– Customers can then upload/send info to me (images, text, etc) either before or after checkout

I’m using shared hosting so don’t/can’t do SSL so I was thinking about just purchasing a stand-alone shopping cart app. But I’d love to integrate a WP plugin into my site instead.

As for first data – I signed up with them as a merchant because of their prices and some reviews… but it turns out that it has been very hard to integrate it into WP.

I was also looking at GoDaddy’s “Quick Shopping Cart”.

Any suggestions?

Thanks,
Jeff