I've said this before, and for you I'm assuming there's no rush, but the best person to sell the "valuable" part of the collection is you.
Now granted, most collections are not art - so I'm assuming you gave fewer distinct pieces than say stamps.
My dad had a serious stamp collection. Had he died with it complete, we would have sold it for a few $ to a dealer. The cost of (him or us) going through it to find "the good stuff would be too high.
Take your art. Unless you've cataloged it, had it appraised, and keep that updated every few years, your heirs will likely just sell it as a job-lot to a dealer. Given his costs, and risks, he'll pick a small number (like $50 per). Your Rembrant is his to find.
What my dad did was sell off the expensive stuff himself before he died (and told us). He knew what he had, and where to find it. (He discovered that selling is different to buying, but that's another thread). At least we knew that what was left was basically worthless and we could donate it with a clear conscience.
When collecting there's a selling price and a buying price. The difference can be -substantial-.
For example, stamps have a catalog. Literally a giant book, with all the stamps and variations, and the current value. (Ahem, buying value). Think if it as a giant "vendor neutral" price guide. [1]
Now obviously when you come to sell you mostly sell to a dealer. So you expect him to take some margin. He has to make a living. But the margin they expect will make your eyes water. (50% to 90% is common). Do test $100 stamp you have is say $10.
But eBay- sell direct. Sure you get more. But still a lot less than book value (partly because scams etc makes eBay risky for good stuff.) And it's it's lot of extra work. Useful for one or two pieces, less useful for 50. (And, of course, scams happen in both directions.)
That's if you know what you have. Selling someone else's collection on eBay when you don't know what you have is equally tricky.
In short, collections are expensive to acquire and hard to get rid of. The value in collecting is the joy of acquiring and having. Collections are (with rare exceptions) not a financial investment.
[1] my insight into stamp collecting died 20 years ago, so I'm guessing this catalog is online now.
I'm a lifelong collector of a variety of (very) niche things, and have at times sold or tried to sell items from my collections, or whole collections at once. You're right about everything, I would only add that each category of thing is its own world in terms of liquidity and how certain you can be of obtaining a guide price. It also pays off to learn about the collector cultures and communities surrounding each type of thing, so you know what obscure periodical or special interest show, etc. to target when you are trying to sell. Never be in a rush, and the other thing that can make a difference is developing good product photography/videography skills.
Patient buyers are another characteristic of long tail markets on eBay.
The pool of stamp collectors etc. is small relative to say guitar players; there’s not an endless September; and buying from dealers is the “socially acceptable” way of starting.
So potential buyers on eBay tend to be experienced bargain shoppers when it comes to ordinary collectability. They will happily wait for the bragging rights price or at least the no way to lose money price.
Sellers don’t control when a sale will happen in the ways buyers do. Once you decide to buy you can — assuming the item is already for sale.
That already for sale part is the difference. Sales have lead times. Even at fire sale prices the decision to sell precedes someone buying. It takes time for the right person to find your item.
Pricing and advertising and marketing can help. But they don’t force the timing of a sale.
I appreciate the advice. My collection is catalogued with what I paid and current-ish fair market values. The future executor will know which handful ones are worth consigning individually and at what galleries, and the rest will likely be bulk sold.
Now granted, most collections are not art - so I'm assuming you gave fewer distinct pieces than say stamps.
My dad had a serious stamp collection. Had he died with it complete, we would have sold it for a few $ to a dealer. The cost of (him or us) going through it to find "the good stuff would be too high.
Take your art. Unless you've cataloged it, had it appraised, and keep that updated every few years, your heirs will likely just sell it as a job-lot to a dealer. Given his costs, and risks, he'll pick a small number (like $50 per). Your Rembrant is his to find.
What my dad did was sell off the expensive stuff himself before he died (and told us). He knew what he had, and where to find it. (He discovered that selling is different to buying, but that's another thread). At least we knew that what was left was basically worthless and we could donate it with a clear conscience.