Did you list it on Afternic? And if so how much? I suppose if it was listed, they would have seen your listed price (inclusive of the registrar's mock up) on a partner site when they first searched to register it.
That they registered the .net and .org implies they are serious about using the name and have already tried the .com and saw that it was taken. So here is
my own take:
- If not listed on Afternic, list it for your desired price before you reply them.
- Do a reverse email lookup on the inquirer to see if you can ascertain who he/she is and what company he/she represents. Having an idea of such information may greatly influence your price expectation. You never know how big the company represented is? Even if you do not get any information, you should still price at what you feel comfortable at cos many deep pockets may still make low ball offers at first. After all, every buyer wanna cut cost and acquire for a low as they can while you on the other hand want to sell for as high as you can.
- Reply them that you appreciate their offer, however, your expectations are in the high four figure range (or whatever range you are looking for). Know that they may make an offer in a low four figure range, hence the reason why I suggested a high four figure.
- If their offer meet your expectation, you may get a sale. If not, you can choose to sell or decide to wait for the right buyer.
- Note that their usage of the .net and .org put more value on your .com. So, even if they do not buy for now, they will still come back later because .com is King
Just my two cents. Hope you sell for a good price.