Silver Price Vs Red Book Price.

I think older (recent edition) RedBook pricing can be of help.
Some circumspection is required, however.

Look at the foreword of the book. There should be some note regarding the then current spot bullion price, at the time of writing.
Determine the then bullion price of the coin, and subtract that from the listed price to get the numismatic premium value at the time of writing.

Mostly, numismatic premiums are more stable than the spot bullion prices.
With this sort of background pricing information, it IS possible to deduce a close market approximation value of the coin you are considering.
Nevertheless, the later the edition of the pricing book you are using the better, because less forward interpolation of the numismatic premium is required.

Add the current ASW bullion price to the numismatic premium you have deduced.

Back when silver was over $45 per oz I had rolls of silver, WL,48&49 Franklins and 200 silver Dollars that I sold. I could have bought them back for less at a later date.
Now I wish I had them back because alot of them were good dates and the melt made them scarcer

ebay is probably the best gauge of a coins true value.

Search for something like a 1995 ASE. After typing the description in the search bar, a a bunch of active listing will appear. On the left-hand side you'll be able to refine your search. Under the "Show Only" section, check the box titled "Sold Listings" and a list of sold 1995 ASE's will be displayed with the price it sold for. Then average out the price and you have your comp.

I agree that ebay is the best way of telling true value. Items are worth what someone will pay (or, how much it would cost to make them give it up)
You have to take an AVERAGE of what something sells for to get a good idea.

I was looking a particular item that I recently bought and found it is worth about $70-$80 on ebay (reverse proof zodiac Ag round)

Now, I saw one sell for over $200, and I also saw one sell for under $30. The $30 one was probably posted at a bad time in the wee hours of the morning.
The $200+ one was probably posted at a lucky time with some rich people fighting to finish a set.

In statistics, those would be called "outliers." Basically they don't fit the pattern.

They are the only 2 I saw that didn't sell in the $70-$80 range.

So what do I say my coin is worth? Around $75.

Now if silver goes up by $1 per oz, will that change the value of the coin? No. The market doesn't swing that way.
Now, if silver jumped $10 per oz, maybe it would go up, but I wouldn't expect $10, or even close to it

The main point is something is worth what people will pay. Trying to divide up what part of the value goes where doesn't work. Junk silver sells for about 20x face on ebay. Mercury dimes will sell for 22x face. $0.20 numismatic value? Not really. When junk silver was selling at 15x face people would still pay around 20x for mercs. is that $0.50 numismatics? Basically all you can say in that case is people pay more for mercs.

So the coins in your shop are 1/2 the RedBook value? I'm common coins of course?

When I started collecting coins(for the 3rd time) back in 2007 I went to a big coin show in Atlanta. There was a dealer there that had 2 huge bins of low grade common date Peace & Morgan dollars. Many had been cleaned and/or were otherwise impaired, but all were for sale at slightly over spot.

We've had this discussion several times & I have always maintained that the sale price of low grade common date coins is almost entirely based on the spot price. In fact, I put my money where my mouth was & listed a few silver dollars that met that description for less than spot in the auction section. They didn't generate much interest & ended up selling right around spot. That's not much of a sample, but at that time & place they were only worth spot.