Elon Musk is the world's wealthiest man, and his life has been in the public eye since he co-founded his company, Tesla.
Mr Musk's ex-girlfriend from university, Jennifer Gwynne, is auctioning off a trove of items from their shared past.
The items include a birthday card Mr Musk sent her in 1995, a dollar bill with his signature on it, and several photos of a young Mr Musk at university.
Along with these items, Ms Gwynne is also auctioning off a 14-karat gold diamond necklace that Mr Musk gave her on her birthday.
Several items now have bids in the thousands, with the birthday card expected to sell for more than $10,000 while the signed dollar bill currently has a top bid of $7,604.
The duo dated while they were both enrolled at the University of Pennsylvania and Ms Gwynne, who is now 48, is selling the items to help fund her step-son's college education.
The auction is set to end on Wednesday.