You have to visit and like more and more pages in Facebook. Make valuable post in those pages. you will definitely gets a tons of likes. Don't need to buy likes by money from any websites. They are not real actually.
if you want to build authority
try to make post engagemant with viral content
you will get likes shares and page likes
if you need only page likes you can advertise on facebook on low cost countries first to get cheap clicks
I post viral relevant videos and create "post engagement campaign "
i buy from the cheap countries real likes to get social proof
and than i go internatiol to get real relevant likes with my social proof post .