Need FAST Reliable cheap ball-joint mech Mesa AZ

Ball joints are out on my F250. They're asking almost $1000 at Reliable Diesel in Mesa. Guy with his own shop advertising on CL (I have had great luck with these kinds of listings and saved a lot) is asking just $550.

Also, Good Sam paid to tow it to Reliable Diesel who diagnosed it. What does Good Sam cover? The diagnosis as well? If I choose to go to a different place is the towing out of my pocket? I'm guessing yes. But still worth it. And if I do have it moved to a new place I'm guessing Reliable will charge me for the diagnosis? I haven't had much car trouble in my life...no idea how all this works.

Anyone know of a good honest mechanic in the Mesa area with great prices?

Thanks!