His Dad
It was his own father who was selling the item. This is how Mike recounts it in a post he made on his social media:
“Just before the pandemic started, without knowing, I bought something on eBay from my Dad, who I’ve never met. He refunded it. Two years later, it started me on a journey to get to know my family that I didn’t grow up with. And tonight I met my sister Erin for the first time.”