Anyone trying to get their hands on something related to the Johnny Depp vs. Amber Heard trial will love this -- one man's courtroom notes, including details not seen on TV, are about to go to the highest bidder.

Larry Forman tells TMZ … he took a trip from Kentucky to the Fairfax County Courthouse in Virginia to sit in on the trial, and decided to jot down his thoughts and observations ... just for his own personal memories.

Larry says it was supposed to be a one-time thing, but friends convinced him to keep going back and writing more notes.

The notebook has about 20 pages per day, and covers days 23-26 of the trial. What's interesting is it doesn't just recall what was said in court, but it shows something the cameras couldn't -- reactions from jurors.

The current bid is over $14K, but the sale isn't final yet ... Larry's decided to donate the highest bid to Children's Hospital LA, saying it seemed fitting since it's related to the case.

Remember, Amber testified she had pledged $3.5 million to CHLA, but still hadn't paid up. Larry says hospital reps are aware of the auction and they're pleased about his offer.

Memorabilia like this has been fetching big prices ever since the trial ended ... one of the used wristbands, from day 23 of the trial, carries a price tag of $850. That's more than a wristband for Coachella!