Does anyone know of a reputable driver to take a party if 4 from Salzburg to Hallstatt (maybe stopping in St. Wolfgang) for a party of 4?
This website is recommended in our Germany guidebook: http://www.salzburgguides.at/Tourist-guides.40.0.html?&no_cache=1&L=1
Christina Schneeweiss, whose contact info is on that list, has a minibus for tours outside of town and is recommended by Rick. Others specifically named in the book are Sabine Rath and Anna Stellnberger.
If you're looking for a Sound of Music tour or other day tours from Salzburg, Bob's Tours is recommended in our guidebook: http://bobstours.com/tours.php
I've used Bob's Special Tours as mentioned by Evelynn in the previous reply, and found them to be very "reputable". With a party of four, I'd suggest contacting them to see what kind of arrangement you can work out. They may be able to provide a custom Itinerary for you.
If you're planning to visit the Salt Mines in Hallstatt, I'd suggest leaving early so you'll have time for that as well as having a look at the town. Hopefully you can spend a short time at Rudolphsturm, the large fortress at the top of the Funicluar leading to the Salt Mine. There's a restaurant there and the patio has incredible views of the lake. There's also a small Museum in Hallstatt that you may also want to visit.