I've always been the Buy-what-I-Like kind of guy. Just so happens that the things I like tend to climb higher and higher in $$$ as my tastes change. My sweet spot used to be around $60-80, then $90-120, and more recently $150-200. I occasionally splurge and go for a $300+ knife, but that's fairly rare.
I've been sort of lucky, in that I've been able to pick some great knives that have gone up in value, if NIB. Not so lucky in that I USE all my knives! Most of my main EDC knives are now worth $100-200 more than when I bought them, again NIB. I feel a little sad at moments, but I've gotten so much enjoyment and use out of them that it's really just a moment of regret at not keeping them safe queens.
Buy what you like, and USE them. Much more fulfilling than watching them collect "dust" in a lock-box somewhere. Give each knife a life worth living. Investment for profit isn't wise, unless you have the knowledge and capital to invest in customs. Even then, it's a roller-coaster.
My knives will be for my kids. Of course, they'll have to pry them from my fingers, but at least they will have a story behind them.