I have a collection that I can see myself parting ways with and want a trusted place to find accurate value because I realize that I have several dozen great and valuable comics.
The best place to find out how much your comics are really worth is eBay. Remember that the comics are only worth what people are willing to pay for them. So even though there’s the Overstreet guide, considered the ‘bible’ for the comic collector, and people buying and selling comics refer to this book when deciding how much to pay for a comic or how much to try and sell it for, the reality is that the prices of old comics are determined by supply and demand just like any other commodity.
So, if I were you, I’d make a list of what you’ve got, make a rough estimate of the condition of each of the comics that you think are more valuable, and then surf eBay for a while to get the feel of how much the comics actually sell for at end of auction.
If you have comics from the "Silver Age’ or "Golden Age’, you should be able to sell them quite easily and get a reasonable price, although I would say that except for the rarest comics or those in top condition even from these time periods, specimens in somewhat beat up shape will not get you high bucks - I’d say that if you got hold of an up to date Overstreet and accurately graded your comics, you might get maybe 60 or 70% of the guide value except for the better condition and rarer comics as mentioned above - the comic market has been somewhat depressed for a while now.
Remember, look at what people are bidding, not just at what the sellers are trying to sell for.