We do Real Estate Signs all over the Metroplex.
The last thing I would use is an auger to dig holes. There is so much crap buried everywhere, the last thing I want to do is drill a phone cable, water line, better yet an electric line that Grampa installed for a light on his old pole sign... or even a sprinkler line.... easy to fix, but why hit it in the first place?
I hand dig them all.
Sand, clay, shale, whatever, and it takes about 5 or so minutes a hole, except where shale rules the day!
I shoot for around $900.00 for a V-Sign 4x4.
Paid in advance.