No, I’m not going to try to sell you dive knives in this post. In fact, if I was a dive knife salesmen, this is the last post I would write.
I read something interesting in a dive book, it might have been Deep Descent: Adventure and Death Diving the Andrea Doria. They mentioned something that is a bit of a mainstay in technical diving:
Never buy an expensive dive knife.
The reasoning is that if you drop an expensive knife, you are likely to go after it. In tec diving, this could mean your life. And working with a knife underwater, especially with gloves on, has a high likelihood of droppage.
I suggest that this "rule" should be extended to recreational diving. For the same reasons, and for one more:
There is very little you will need to do with a knife that requires an expensive one.
If you’re trapped by a fishing line, a cheap steel bladed knife will cut it just as effectively as an expensive high-grade alloy.
I imagine most advantages of an expensive knife are in the longevity. This is a good consideration when buying anything, but I still say go with the cheaper options. A little care can go a long ways to increase the knife’s lifespan, and no piece of equipment is worth your life.