i have just picked up my guitar from derringers. took it to get new strings as i had no idea what were on there. i could not figure out if they were really expensive or really cheap. dropping off they were not very open about judging the price of my strings just said they were unsuitable for my guitar. the strings they gave me cost $10 and they charged $30 for changing them. Is this standard?? on picking up they told me the strings I had were jazz strings and are priced at like $30 set. I am wondering if maybe they should have looked at the strings and said 'leave them' and maybe charged me for tuning?? does anyone know much about flat wire strings?? jessa