As they say... "Your mileage may vary".

You should be able to get some ballpark estimates over the phone. There are a lot of tricky subtleties that come into the mix. You should have the guitar properly set up as part of the installation. The strings have to come off the guitar to do the work, so you should get a new set while you're at it. The intonation should be checked. The pickup needs to be set at the right height. Too close, and the magnets pull on the strings, damping the vibration and killing the sustain. That can even make intonation very difficult. Too far away, and the tone gets thin. The solder connections should be neat, clean and bright (no cold-solder). And while the controls are out in the open, they should be cleaned. A tech will usually do all this as a normal part of installing a new pickup. It's not just a matter of stuffing it in, and hoping for the best. A professional job does make a difference.