If they're inaccurate, their price is irrelevant. The last time I used one of these, it was Geoestimator. It was on an insurance claim that was in the 40's squares. We convinced the Adjuster to go with the Geoestimator numbers only to find out later they were around 5 SQ's short on a 30 year laminant. So it cost us $1,500 as the Adjuster refused to do anything since he agreed to use our numbers to start with.
With that said, as far as I'm concerned, that report cost me $1,550. It was the last report I bought from any of them. The guy at Geoestimator, Chad was his name, had nothing to say except they were working on some things. The prick didn't even offer to refund the money I paid for the report.
At $250 to $325 per square, 5% isn't close enough for me, particularly when they always seem to miss low. I don't remember EVER having a report or seeing a report from one of these companies that missed high.
I've given serious consideration to opening something similar myself. Were I to do it though, I would require people to provide some ground photos (to catch portions that are often hidden on the aerial images) and to measure their own pitches. Perhaps I am too much of a fanatic about accuracy but at the money involved, I don't know how people can even think about being casual about it.