That's kinda what I have done, but back years ago in my baseball card days I got spoiled by the Beckett's price guides. You could look up stuff and see the "book" value based on condition. Realistically you could figure that you could sell stuff for about 1/2 book value or a little more depending on what it was and feel that was a fair price. I wish there was a resource like that for knives but I guess there is not.
Candidly speaking, I don't know if any printed material hardcopy guidebook is going to be accurate in pricing knives since a lot of factors go into those prices on secondary these days. When a maker is hot, their knives command a higher secondary price, but just as quickly, they can be overshadowed by the Next New Hotness (NNH) and suddenly their knives are sitting unsold until sellers start dropping their prices. Then, you'll have situations like we're collectively in now, where knives have to be discounted on secondary* in order to move, and many aren't selling at all. There are an awful lot of unsold knives on the Exchange right now, making the value essentially very low. It's why these days, if I want something mainstream, I try to buy it on secondary at a cheaper-than-street price because I know that I'm not going to get much more out of it if I decide to sell. It's also why I don't buy many knives at
all these days, because I have just started purchasing those knives I genuinely want to keep around, because the days of just being able to discount a knife (purchased from an e-retailer at street price) 10% and it sells are over. I no longer buy knives "just to check out" because I don't want to be stuck with something I'll have to take a huge bath on if I decide I want to move it along. Hell, even CRK knives aren't the dependable "You'll totally get all your money back!!!!" holders of value they once were.
So, to recap, a lot of factors are going into what sellers are pricing their knives at right now, and as others have suggested, I recommend checking Ebay for pricing. Arizona Customs is another decent one, but the issue is that a lot of those knives will sell for less than that price if they've been sitting, because you can email them and make offers and most of the time (again, especially if a knife has been sitting) they'll take it. I know, I've done it many times.
* Unless, again, it's one of several hot, popular models