How do I accept one payment and block out a secondary purchase.

[mobiledan]

I am selling single item products and would like to know how to accept the first purchase and block out any secondary purchases for the same item. The reason for this is, I may not be available to change the product to sold out before someone makes a secondary purchase. I would have to refund the secondary order back to the customer. This is bad for business when a customer has room to complain that they paid for the item when it should be posted as sold out.

[snowshoe]

If you're using the online button creator to generate your item button code, there is an inventory feature in Step 2 ot the button creation process.  We use this feature all the time as we sell one of a kind items.  Note, this is a basic feature, nothing fancy however, it works fine.  When the item is sold out, should another customer want to purchase the same item, he or she will see a notice on the PayPal Checkout Screens, there's no interface that automatically displays sold out for your web page, just the notice on the PayPal Checkout Screen.

If you need more robust features, then you may want to look into using a 3rd party shopping cart.  Many 3rd party carts have a backend database for managing your inventory.  They can also display an inventory count on your web page or even automatically display that the item is sold out before going to the checkout screens.