While I've never sold a figured bigleaf maple log, it is some of the most valuable wood in the world, if it is the highest grade. The most preferred figure is "quilted" Electric guitar makers will pay up to $100 for a 2.5 bosrd foot piece. Anyhow, I heard of a log truck load that sold for $18,000, and one log that fetched $10k!!! Out here, there are maple thieves, who will hook up a flexible pipe to their chain saw mufflers and route it into a bucket of water, to mask the noise.
I just bid ~$4000 on 5 large fir and 2 hemlock. Probably 6000 board feet, worth $4000. I may need a 110 ton crane to get them out, but should still net about $6000 for the job, which should take 3 days. If we had to make firewood out of the trees, the bill would probably be $10,000.
Tom, for me it is not "on the side" Any marketable log is money for us. I'd guess I've sold a quarter million board feet over the years, just a pittance compared to a logging outfit...but more than most certified arborists, I'm sure. I've only had a problem with metal a couple times. Once, when I complained and asked the sort yard to cut the metal section off, the buyer simply gave me the full value, which was ~$1000 as it was a big fir log, and that was when export fir was bringing up to $1260 mbf.