I haven't sold any coins in quite a number of years, but when I did, I found that selling to a Dealer nets about 50% of Red Book (or something near "bullion", whichever is higher)...assuming he/she needs the stock. It's always a shock hear that first offer! Personally, if I were going to sell coins, I might try eBay a few times to see how it goes. I might list a few on the site of an experienced eBay friend...to learn the basics and avoid any "obvious" missteps.
I still don't think there's that many people with collections this large out of the entire US population. Out of over 300 million people, do you think 1/2% have a 50K+ collection? That'd be 1.5 million. That's way too high. 500,000 people? Still way too high. I guess it depends on how much you consider to be 'a lot of people'. It probably gets down into the single digit thousands, if that. If that's a lot out of 310 million people, maybe I need to adjust my perspective. How many serious coin collectors are out there to begin with?
In today's world you have to think glodally. These large auction houses draw large numbers of collectors from all over the world. I spoke with Matt Orsini at Spinks durring their last large auction. He is the guy responsible for coins in a Spink Smythe auction including setting values. We spent a moment talking about a couple of coins I was interested in prior to me bidding on some other items. He told me that many of the buyers of these specific coins were high end Chinesee collectors. Again while waiting for another item to come up they had some bidders from the Middle East. They (in the 50K range what I would consider semi-serious collectors) are out there probably in bigger numbers than you think.
Once i was counting how many $10k plus coins that was sold at heritage, i counted over 500. $50k collection is probably small fish for heritage. on some of the smaller auction house, you might be able to get auction named for you. post a photo of your most valuable coins.
I think that if $50,000 was "small fish" to Heritage, their minimum consignment would be higher than $5000. But then, that's just my opinion.
Any catch is a good catch... just some are great catches, then you have amazing catches... HA will take anybody who makes it worth their while, but probably won't travel out to you unless it's a collection worth mid six figures.
While I agree 50K may not be a big auction figure for major auction firms, it is their bread and butter. It's the small auctions that pay their bills, not the large auctions that may come along once or twice a year. It's the same with any business.