While there's no shortage of Mickey Mantle autographs in the marketplace, there's truly a unique item on the auction block at Lelands ... a 14" x 20" cardstock signed 99 times by the MLB legend, which includes a special message about the crappy writing implement he used for his John Hancocks!!

Number 7, one of the greatest baseball players to ever step foot on a diamond, signed his famous Mickey Mantle autograph decades ago for a buddy who operated a company that sold statues.

Mantle, using a black felt fine tip marker, signed his name on the cardstock 46 times ... before calling an audible (we know, wrong sport).

"THESE PENS SUCK" ... the slugger wrote with an arrow pointing at his previous signature.

Then, seemingly not missing a beat, Mickey continued signing his name 53 more times ... 99 times in total.

FYI, Mantle was known as a perfectionist who had immaculate handwriting. Just look at the photo ... beautiful penmanship.

Now, the special item is available for bidding on the auction block ... but it won't come cheap. Although the starting point was $10K, the item will ultimately sell for exponentially more.

In fact, the cardstock has already been bid on 37 times, with the price already sitting at $70K.

Mantle, a 20-time All-Star and three-time AL MVP who won seven World Series, passed away in 1995 at the age of 63. Mickey signed a bunch, especially later in life ... but, good luck finding a better backstory than the one behind these autographs.