The best thing
you can do (as a seller) is setup your own website where you have a store and you sell code through proper SSL. Have a business PayPal account and have all appropriate verifications, etc. through PayPal. When transactions are made, you will have purchase evidence and they can't simply say, "I didn't get the code." or some other crap. I recommend setting up email verifications, order numbers, etc. all to assure there are multiple deliveries of the code.
When I hire individuals, I have them work on a test server (hosted on my personal PC) with access through WinSCP, or I ask them to work on TeamViewer. Never do I pay before hand because of quality assurances. For large tasks, I may make a down payment (e.g. 20% upfront). However, I am a fairly trusted member amongst OtLand (and several other forums). So, perhaps I am one of the few exceptions to the whole "Jobs" section dilemma.
When it's all said and done, you honestly have no assurances when it comes to "sending" payments via PayPal. Purchasing something on a legitimate website is another story. You'll have a greater chance avoiding chargebacks that way.
The only method via PayPal that cannot be charged-back/disputed is MoneyPak. These are prepaid cards you buy at a physical location, and once sent, cannot be reused or charged-back.
Other methods such as Western Union or MoneyGram are excellent for avoiding charge-backs. But most people don't like using these services because they have no assurances you'll finish / complete the work. This is partly why I never pay upfront. People tend to take longer than expected or walk away and never pay you back.
@Archez owes me $250 from a few years ago, which I believe it's safe to assume, will never be seen again.
