So you have got hold of an excellent marketable domain name with excellent potential. You have already assessed a ballpark of domain name worth and you are ready to monetize on this domain name by selling it.
The first question is where? In todays vast internet space there are many auction and specialized auction houses which sells domain names with or without the content included (a website). Most of them (all of them) are taking commission from the sale price and providing escrow like service for domain name transfer.
The most recognized in the market is Sedo.com. Sedo takes 10% commission of the sale price and provides escrow services. It also is the most searched domain name broker thus listing your domain name on Sedo is half the job done already. Note that minimum commission on Sedo is US $50 meaning if your domain name price expectancy is under US $500 you should probably look elsewhere.
Second option is market the domain name yourself and use escrow service like Escrow.com for sale and transfer. Escrow.com is recognized for its hassle free sale setup and domain name transfer and they take minimum of US $25 and there is an option to split the Escrow.com commission fee with the buyer. I recommend Escrow.com if you have under $500 priced domain for sale – and make sure to ask the buyer to split the fee.
There are also other options in the play – for example Ebay.com for really bargain prices or going through the registrar auctions (GoDaddy.com for example has bought TDNAM auction house few years back) but I cannot say much about them since I never have used their services.
We at Vastus Domains use Sedo.com and Escrow.com daily and can recommend both.
Alternate option would be to have the site show sell page and your PayPal.com account email and price. If you have relatively popular domain name you could save on commission this way but on the other hand you have not established a trusting relationship with the buyers so this might turn off some of them.