Welcome to WebmasterWorld Guest from 18.104.22.168
The question back to you though - is it worth it to sell it? How much time do you put into this domain name? How does it make your money? And the time - does the money you make compensate your time fully?
1. How did he come about this domain
2. Why dose he want this domain
3. Any other conditions for buying the domain?
4. How do you prefer to pay for the domain
Well stay clear of that person if he persists on domain appraisal from a set of 1 or 2 specific appraisal companies which you haven't probable heard of. (Most cases they would just try to sell their services to you while they are not genuinely interested in your domain)
Always prefer to sell your domain through escrow dns. It would save you a lot of time. I wouldnt recommend paypal.
You must calculate the price on your domain name not just on the annual revenue. Your website is 10 years old. that is a huge plus. Besides what is it's page rank and alexa rank?
Try posting all the details on forums like site point or something to get an average estimate of your domain name
never sell for just 2* revenue. Mostly i guess the buyer wants to flip the domian. 10 year old domains may be well worth over 10-20 times the average revenue