How much did Martin Luther King pay to get out of jail during the Montgomery bus boycott?

$1,000 bail

Dr. King and 89 other African-American community leaders were arrested under a 1921 Conspiracy law that prohibited boycotts of lawful businesses. Dr. King was fined $500 plus $500 court costs, or sentenced to 386 days in jail.

Dr. King decided to appeal the case, converting the sentence into 386 days in jail; however, the original court documents seem to indicate he was released on his own recognizance prior to the trial and while the matter was under appeal. The Alabama Court of Appeals rejected King's hearing in April 1957, because his lawyers missed the 60-day filing deadline. He was then charged $1,000 bail, possibly to ensure he reported to jail at a certain date, or to give him an opportunity to decide whether to pay the fine or take the sentence. King ultimately paid the the fine in December 1957.

The State of Alabama arrested Dr. King again in 1960, on trumped up charges of tax fraud, a case he later won in court. Bail for the second set of charges was $2,000.