Write a contract to dissociate all liabilites from a transaction?

Hello. I'm selling digital assets online and I use PayPal and I have had cases in the past where the buyer files a dispute with PayPal and claims that they never received the item. Unlike items that require shipping and can be tracked, it is, legally speaking, very difficult to prove that a digital item has been delivered and so almost every dispute always goes in favor of the buyer. When you submit PayPal invoices however, you can enter your "Terms and Conditions" that apply if buyer pays. I'm wondering if there is a way I can create a binding contract that makes all future transactions undisputable. Is there a way for me to completely dissociate all liabilities as a seller and have the buyer agree that he cannot dispute no matter what? I realize that such a contract would mean less customers, but I'd rather deal with fewer but safe, than many but risky. Thanks!