It's basically been stated already, but you'll mostly have two kinds of people come to your table: Those who have no idea that a knife could ever cost more than $20 (or understand why it would), and those who know generally what the knives ARE worth, but are looking for a deal.
You probably won't sell very many to the first group, and the second will usually only pay if it's a specific piece they've been looking for, and if it's at or under the lowest price they can find on ebay or amazon.
I usually fall into the second group at a knife/gun show. I will mostly shy away from the tables where people are selling "collections", because 9x out of 10 I see them at every show with the exact same pieces, remaining unsold. Why? Because they want what THEY think they are worth, not what 99% of buyers think they are worth. In other words, they're not really interested in selling them, but rather in showing off a collection, or trying to make a large profit on something they themselves got a deal on already.
The tables I WILL go to are distributors, who I know paid only 50%-75% of MSRP, and can probably come down another $15 or $20 if I buy a couple of pieces off of them.
Now, I'm still figuring that I could probably get close to the same deal on any one of dozens of online retailers (amazon and ebay included), but this way I know exactly what I'm getting, can handle the knife, and save the cost of shipping, plus maybe another 5% or 10%. Instant gratification costs a couple bucks too...
The other tables I go too are people just selling a lot of used pieces for what are actually great deals... Half of new price for a piece with minor wear, or something that I can easily sharpen and polish up to almost new.
I was once at a table filled end to end with knives, and saw a couple of Kershaw Autos I'd been looking for. They were recently discontinued and the guy was asking about $25 or $30 more than they used to regularly sell for. I was debating paying close to what he was asking when I heard a younger kid ask if he could take $5 off for the same knife. The dealer started saying how they were a high demand item and would take weeks to restock, so prices were firm. I immediately walked to the other end of the show where another dealer had the same knife and was willing to let it go for about $5 less than I had seen them selling for before they were discontinued. Now, it wasn't the exact color I wanted, but I wasn't about to put up with a seller who was probably already making at least 25% on a knife, and couldn't come down a measly $5.
Just a little food for thought. If you want your knives gone, you need to be willing to negotiate, or you may as well just list them individually and wait for the buyers, deal with shipping, future price drops, etc...