I have no experience selling domains, so I have no idea what your sites are really worth. However, I just wanted to mention that I had an email earlier from a "Marc Shavell" saying he was interested in one of my sites. I did some research and it would appear that it's part of an appraisal scam. Allegedly, when you respond, they make an offer, but say it has to be appraised by an independent appraiser, one they trust. They provide you with the name of the company. After you pay for the appraisal, they say they are no longer interested. One of the posts I found said they offered 12,000 for the site. Point is, if it sounds too good to be true, well, it just might be. Be careful.
I hope it's a real offer for you.