Here is a recent email reply that I sent to an interested party for one of my domain names, which they were interested in my offering price. I hope this helps you in one way or another and gives you an idea of how I reply. I have not changed anything in the email from the original email that I sent.

"Hello Shelley,

 
The current buy it now price for KidsCards.com is $3,850 USD. You can visit the domain names listing page here http://www.afternic.com/name.php?domain=kidscards.com which is a 3rd party listing service which I like to offer as they handle domain payment, transfer of the domain name to your account and safety & security for both parties. I also use an escrow service (EscrowDNS.com) which also handles all of the above if that is easier for you.
 
The reason behind our asking price, is due to the generic nature of the domain name KidsCards.com that matches very well with what people search for and know already. On the internet, it is Key to have a domain name that matches what people already search for and know, is clear and easy to spell, makes sense and is to the point.
 
KidsCards.com is all that and then some!
 
A very recent sale of the the domain name KidsCard.com for $2,500 USD also backs up our listing price (proof of sale, under :Additional AfternicDLS Sales Between $2,000 – $4,000). We feel KidsCards.com just plain makes more sense and is a better domain name then KidsCard.com . If you are offering Cards for kids, you wouldn’t just have One Card on your site would you? We wouldn’t think so either and that is our reason why we think KidsCards.com is a much better domain name.
 
I look forward to working with you and if you have any questions at all, please feel free to ask.
 
Best Wishes,
 
Jamie Zoch"