Flippa , Sedo and Fiverr will be the place for you to sell those domains. But i personal think that flippa will be more easy to get potential client.
sedo.com afternic.com dodaddy.com namepros.com dnforum.com i use all of them, at forums you will only sell reseller/bargain pricing
Do we have to pay first the fee at flippa?? i guess whether we got the bid or not... they will charge you also right? 19usd per list is quite bit high just for listing. and 5 % success fee... flippa making a lot of money alone with listing only