Someone on ebay has been trying to sell that exact Earnhardt knife for $75 for the last month, but has gotten zero bids. So, I think it is safe to say that knife is worth less than $75. As Ken discussed above, manufactured commeratives & collectibles are very fun to collect, but lousy investments.
Selling a large collection of anything can be a very difficult and time consuming task - especially if you are trying to get top dollar. You can spend years doing it, and that means that the reality is that unless it is a collection of very, very valuable items, it will probably not pay off for the time it will take to do it. The reality is that a collection is never worth as much to anyone else as it is to the original collector that built the collection as a labor of love.
If you want to sell them fast, then put them on ebay for no reserve and you get whatever you get. You will still need to spend the time to take the pictures, write the listings and pack & ship the items. You could sell them in groups to minimize your effort, but that will lower the price. If you want top dollar, then you will need to research each knife to determine maker, pattern, year, handle material and any other key attributes, then either list it on eBay or here at AAPK. There are people that might buy an entire collection from you, then resell them at knife shows or online. That is by far the easiest way to turn a collection into cash, but you will also get only 30-50% of the potential retail value of the collection. There are a couple of guys here on AAPK that might be interested in that sort of a deal (or at least there was before the pandemic). I doubt there are many (if any) knife shows happening right now.
"The Luggage had a straightforward way of dealing with things between it and its intended destination: it ignored them." -Terry Pratchett