How much does it cost to get into police academy?

It doesn't cost anything to attend the police academy.

Additional: The above is misleading. ONLY those departments/agencies who conduct their own academies do so without cost to their prospective candidates who have already passed their basic hiring standards and who are chosen to attend their in-house academy.

In many jurisdictions accredited "private" schools teach law enforcement courses sufficient to pass their states LEO certification examinations. Upon successful graduation and passage of the state exam you MAY apply for employment to certain departments or agencies. SOME of them will reimburse you for your out of pocket expenses for your schooling and certification - IF you sign an employment contract to remain with them for a certain length of time. Since these programs and schools and their costs vary widely you need to contact schools (or police agencies) you are interested in and ask.