Thanks Phoenix, that was just the info that I was looking for.
I don't use Storez for customers with such basic needs.
All things considered I think I'll take that piece of advice, and for now just create a button to Paypal's single item checkout, and let Paypal handle it all - which is what my client wants.
I'll hold back Storez for this client until/when/if they grow into multiple item orders.
Thanks again for your help!