*Points to the site he's on being CoffeeCup Software* well duh! CoffeeCup's Shopping Cart Creator I would think would be the answer for most of your questions
Ok not to be so silly lol, paypal's standard setup will work just fine for what you're wanting regardless of the size of the shop. If he's only doing a few items and not restocking them or even if it's just a few as in 2 or 3 things completely, then you might find using the Paypal buttons easier than using software for a shop and less hassle and work (well maybe lol not sure, haven't setup a button in Paypal in quite a few years so it might be just as much work lol).
Just a few tips how nice the Shopping Cart Creator works:
You can copy and paste the products and just change the few areas such as Item Numbers if you have any assigned in the Titles and descriptions, change the description for the new product, pricing and you're done. (Don't know if Paypal has a dupe type setup that allows you to copy their buttons or not)
It's very easy to setup, you can have a shop up in less than an hour, and in the case you're talking about, probably half hour, as long as you're using an included template. You can purchase the Shopping Cart Designer ( I would suggest the Pro version for maximum customization features ) and create your own template, or alter those that are included as I did. Doing that it would take a little bit more time, but even that program is pretty easy to figure out after you play with it for a while.
You don't need to enter any ID & PW for paypal into the program so the client (person(s) you create sites for) doesn't have to share that information with the site builder. All that's added into the shop information for Paypal is the email address and the choice of which types of payments to receive and the type of payment processing you want to use (in other words standard etc.)
Pretty simple setup, and the Pro version that is coming soon will have a lot more features to work with also. Worth the price and the effort if the person(s) you create shops for have more than just a few little items to sell and even then it's a nice setup.
Hope that answers your questions and if not please ask some more