How can I determine the price value of my comics?

I have a couple comics(dozens) and I want to sell them. How do I determine how much they are worth for collectors? And I want to know with sum sort of site, not going to my nearest pawn shop, or old school pawn shop thing. I want to know either thru a web, or by calling a specialist or sumthin. Plz, no sites that acquire my cell or home phone, or credit card payment(or any payment of any sort). Thanks to those who explain in detail. 🙂