I'd occasionally have service work at a couple of coin shops in my area. At different times people came in to sell a collection of silver/misc coins from a late family member. Bag/container of - say for example - normal circulated, worn, Mercury dimes, plus assortment of other stuff. Shop owner would ask if they'd sorted through to set aside anything potentially collectible - answer was always "no". Shop owner would then explain silver content of the coins, pull up current spot price, and further explain that they would only pay X% below spot. Customers would always ask about potential collectibles - shop owners always said that they didn't have the time (wasn't worth their time) to go though a whole stash of coins to potentially dig out 1-2 that could give them a few extra bucks.
It was said something along the lines of, that a person would have better odds of winning the lottery, than finding something of significant value in a hobby collector's stash. However - if it was a true coin collector's stash, where they are sorted/graded - different story. But most all hobby collectors pick up standard circulated coins.
Saw this as well in regards to firearms - when my dad passed a couple years ago, I was in charge of disposing of his collection. Yes, my brother an I picked out whatever we wanted, but there was still a lot of basic hunting rifles, etc., that we had no use for. Ended up selling the entire lot for what worked out to around $200 per firearm. I totally understand that the dealer was going to have to check each one, do any cleanup/repairs, deal with potential buyers buying on payments (or trading in other guns), and they have to make a buck as well.
Summary; if you sell to a coin shop, you're going to get less than if you sell the coins by the piece, and less than if you sell to a private party. Get a purchase price estimate from a couple shops, and then use that for a starting private party price.