Paypal & instant payment notification

Hello, I have a customer who wants to implement Paypal instant payment notification on his website. Basically, he wants a script that emails a custom message once a customer purchases an item. Instant Payment Notification has the ability to do this. However, I have a couple of questions: -- Is this really the best method? We're going to implement a shopping cart on the site, too, so Paypal might not be the best solution. -- Does anyone have sample code for Instant Payment Notification? If you'd like more information about Instant Payment Notification, you can go here: https://www.paypal.com/cgi-bin/webscr?cmd=p/acc/ipn-info Note that this requires you to login with a Paypal account. Here's a brief synopsis taken from the above page: How It Works When a customer makes a payment to you, PayPal will post a notification to your server at a URL you specify. Included in this notification will be all of your customer's payment information (e.g. customer name, amount) as well as a piece of encrypted code. When your server receives a notification, it will then post the information, including the encrypted code, back to a secure PayPal URL. PayPal will authenticate the transaction and send confirmation of its validity back to your server. After you have activated Instant Payment Notification, your server will be sent a notification every time you receive a payment, this notification will be sent as a hidden "FORM POST" to the URL you specified, and will include all of the payment information. The FORM variables for the notification are listed below: To me, this seems kind of like a hack -- i.e. there should be a better way to do this, perhaps as part of a (free or low-cost) shopping cart and payment prcoessing system. Also, there seems to be no way to test this without sending the Paypal user money. (I am going to contact Paypal about that one.) Any experiences, good or bad, and advice would be appreciated. Thanks! Erica Remove SPAMFREE- to email me.