I was buying rechargeable batteries on eBay and was not an eBay plus member.
When I was about to check out the $22 purchase at the checkout page, there was a clickable link from eBay: get $20 off your purchase by joining eBay plus.
I clicked the link and joined the 30 day free trial eBay plus by providing my PayPal details for a voucher code I can enter to discount my purchase so I only have to pay $22 - $20 = $2.
After the purchase, I cancelled my eBay plus membership immediately so I won't be charged with the $49 annual fee payable at the end of 30 day trial period should I choose to continue.
Good title. Great story. Liked the punchline.