Kim Kardashian -- Mystery Buyer Wants Sex Tape Off The Market

Someone is looking to buy the rights to the Kim Kardashian sex tape from Vivid Entertainment ... claiming they're willing to pay big bucks to "completely remove it from the market."

TMZ has learned the mystery buyer has hired a lawyer in Tennessee -- who fired off a letter to Vivid honcho Steve Hirsch yesterday which reads, "I was approached by a private party who has asked us about looking into the possibility of acquiring all rights of the Vivid, 'Kim Kardashian Sex Tape.'"

The lawyer adds, "The party we represent does not intend to distribute or broadcast the 'tape,' but hopes to completely remove it from the market."

The buyer also wants to purchase all of the raw, unused footage (sex tape outtakes) that never made it to the DVD.

The lawyer never identifies his client -- but leaves a giant hint ... writing, "We would purchase any other footage you may have control of that involves Ms. Kardashian."

The lawyer NEVER mentions the other person in the tape -- Ray J.

Sources close to Kim wouldn't tell us if the reality star is the mystery buyer ... but did reveal that Kim has previously shown interest in buying the rights to the tape.