After reader Chapter 4, all I can think about is how Maho picked out her guitar. So many people pick out expensive guitars because they look cool and have a known brand name, but they don't actually try to PLAY the thing to decide if they like it. If you don't like how it feels or it sounds you won't wanna play it, regardless of how cool it looks! Sorry, this is all irreverent to the story but this kinda thing drives me CRAZY.
Riko OBVIOUSLY has an extensive background of music and instruments that she'll most likely make the guitar sound good by tweaking a few knobs at the amplifier's EQ.
Also, PRS guitars aren't all looks. They have a wide thin neck (most of their models, at least) that is good for beginners and they sound really great.
But yeah... almost 772 dollars is expensive.