What's the go with discount codes?

I just had a buyer who just purchased one of our PC's but hadn't paid yet to add in a $50 discount code. I haven't had this before. Can anyone fill me in what this is all about?

No need for you to worry as you will still receive the full amount.

PayPal and ebay give buyers discounts when they purchase higher value items.

Thanks very much for the response, much appreciated.

 

Discount codes aren't just for high value items either.

 

These ones are just given to random id's.

I have one for: 10% off your purchase of $1.00 or more, up to AU $50.00 off