Welcome to CCF! Vcoins has dealers that will make offers or perhaps sell at Vcoins auctions with commission. CNG coins will make offer if you want to sell direct to dealer.
IMO high grade expensive coins would do better at auction. Low grade rather common might be easier selling them directly to a dealer.
Dealer offers, like other product/collectible businesses, will tend to be a wholesale price so they can mark up to current retail.
There may be a CCF member dealer you could work with that has a
ebay store or online store. I know some don't care much for
ebay due to fakes, but there are legit ancient coin dealers there. I just checked
ebay sold auctions, a Julius Caesar denarius, slabbed, recently sold for about $2,500.
Through my years of collecting I saved the seller's photos or took my own so I have pics of them all. Someday when/if I decide to sell, I can mail a flash drive with pics of my collection to dealers so they can get a idea of what I have. I know some dealers will travel to look at collections if they are considerable. Obviously auction houses will have directions how they can examine the collection, mail them insured with a itemized list you made, etc.
I also have a lifetime Julius Caesar denarius but not slabbed.