What is awarded for Guiness world record?

No prize is awarded for entering the Guinness book.

Just for reference you can check this article:

LOS ANGELES, Dec. 6 (Xinhua) -- Three Southern California men have broken a Guinness world record for continuous TV watching, having stared at a screen in a special Plexiglass theater for 86 hours and six minutes Monday.

Farris Hodo, Kevin Cood and Victor Lopez outlasted 97 other contestants to earn the record as the endurance contest concluded four days after it began three days ago at the Hollywood & Highland central courtyard. Each of the three finalists was awarded a Guinness World Record certificate and 10,000 U.S. dollars in prize money.