I bought a used guitar today and if I hit high notes, I don't get clean sound, instead it sounds like the string's touching the fret and makes buzzing sound. Plus, higher E strings play the same notes whether I hit 19th, 20th, or 21st fret. They all play 21st.
What could be the problem and how much would it cost to repair this problem?
Sounds like you need a truss rod adjustment, or to have the action adjusted. Cost depends on where you take it. Each shop charges differently. At least you have an idea of where to start.
My Main Gear:
ESP Eclipse II
Jackson RRT-5
Dean Michael Schenker Signature Yin Yang
ESP LTD EC-1000 Deluxe
Gibson 2016 Les Paul Traditional T
Marshall JVM 410H/1960V Cabinet