Greetings Wendy:
Well, I'm always skeptical of anyone who offers money for a yard tree. It is very common for yard trees to have numerous defects, including butt rot, metal, bird peck, mower damage, etc.
Moreover, I'm worried that the gentleman who approached you is uninsured and potentially not who he claims to be? Is he a licensed and certified forester or is he simply a logger? Is he a certified arborist? Does he have liability insurance in case he drops the tree on your house or your neighbor's house? Can you get his information and do a background check on him?
My standard recommendation for anyone interested in selling and marketing their standing trees: contact a professional state or consulting forester and have them give you an on-site, unbiased appraisal of the trees you would like to sell. True, you might find out your tree is worth more as firewood, but you might find out that your tree is really worth $2000.
Do yourself a huge favor, contact a local state or professional consulting forester for an on-site appraisal and evaluation.