The term “setup” can mean a lot of different things and is sometimes confusing. Some music shops do a basic setup that includes a restring and maybe a basic neck adjustment and sometimes saddle height changes. That kind of basic setup can usually cost $30-50 and is fine in-between regular services if you keep your guitar well-maintained. Most repair shops and some music stores do what I call a full-service setup which is a comprehensive inspection and adjustment of all parts on the guitar.
Our 20-point full-service setup includes: taking off the old strings, giving the whole guitar a good clean, conditioning the fretboard, polishing the frets, tightening all loose screws on the body and headstock, restringing, checking neck and truss rod for proper alignment, setting string action at the nut and bridge for best playability, setting the pickup heights, adjusting the intonation so the guitar stays in tune all the way up the neck, checking and cleaning all electronic components.
Your guitar needs regular servicing just like your car does, especially with the climate here on the coast. The timber reacts to the changing weather/humidity and the metal & electronic parts can corrode if left alone in this salty moist air. A good setup will keep the guitar playing like it should and will stop premature aging.
Its also worth saying that a good setup will take into account the style and preferences of the player. Someone who plays light can have a lower action with strings closer to the fretboard while a heavy hitter will need the strings a bit higher to avoid buzzing. The more a string moves because of bigger gauges or hard playing the more likely it is to make contact with the frets when it vibrates. Some players prefer lower action even if it means a slight fret buzz, where other players want no fret buzz even if it means higher action. Our job is to find the right balance and give you back a guitar that plays better than the day it was made!