Recently, I discovered http://www.mals-e.com who provide a free shopping cart integrated with PayPal. You can create your own button or form to launch shopping cart. Shopping cart setup is not difficult for a person who knows little programming. In cart setup you can set minimum items a visitor must buy.
For example, I set shopping cart to my traveling web site to sell images and set minimum items to 7. If visitor will try to check out with less then 7 items, shopping cart will not allow it.
In button code, or on the HTML form you set price for the item and a page to which visitor will be redirected when she clicks Continue Shopping link on the shopping cart.
When user clicks "Go to Payment" button, the form for required information will be displayed. After the visitor fill all required information and click the CONTINUE button PayPal login page will be displayed. The visitor logs in PayPal and pays. Then she must click Return to Merchant link to return back to your web site. Payment receipt will be sent to her email.
Shopping cart setup allows you to choose to which page of your web site visitor will return.
You can go to my site and try my shopping cart to see how it is working. Set Schopping Cart Example