If you want to become truly great at playing acoustic guitar, you should try to learn from people that have mastered the instrument. There are plenty of guitar players that you can learn from in this respect. David Gilmour is a great guitar player who was a part of the band Pink Floyd, and he is widely known for being a tasteful acoustic guitar player that always knows how to treat the instrument like its own unique item rather than being an unplugged version of an electric guitar.
Paul Simon of the band Simon and Garfunkel is also without a doubt one of the best acoustic guitar players of all time. The syncopated rhythms and the mixture of plucking and strumming that he goes for in his deceptively simple playing style ended up becoming iconic in a generation was a precursor to flashier styles of playing. The thing that made Paul Simon great was that he did not need to show off. Instead, he gave the song what it truly needed and played according to the requirements of the music that was being created, incorporating his own lush chord structures into the mix as well while doing so.
You should also check out classical guitarists such as Francisco Tarrega. Tarrega was a great classical musician who was widely known for having legitimized the guitar as a beautiful instrument. It was previously considered to be quite low culture, the stuff of bards and crowded halls. However, Tarrega played so beautiful that people were forced to acknowledge that the acoustic guitar actually did have a lot to offer them.
The truth is that the best acoustic guitars under $500 are all you are going to need in order to start playing like the greatest players of all time.