Volunteers spent Saturday searching for the 15-year old girl in and around the Morgan Hill area. San Francisco 49ers Alex Smith and Joe Staley took part in the search.
Sierra's family announced the reward Saturday and said it was made possible through donations.
"We want someone to come forward without this, but whatever we can do to get some kind of clue or tip that will lead us to Sierra, that's what we're after," Sierra's father, Steve LaMar, said.
The LaMar family continues to hope that an army of lawmen and volunteer searchers will find a lead that brings Sierra back to them
Sierra was last seen March 16 leaving for school. Investigators are looking into several leads in the case.