I've got saved ebay searches as generic as "spyderco", to the even more generic "(8cr, 9cr, 440c, d2) knife". While I often will be searching for a deal on one specific knife, I've found that just keeping my options open and snatching up anything that fits my criteria at a good price leads to good times. I get to handle a bunch of interesting and varied knives and then trade / sell up to try out more.
I bought a Cold Steel Kudu and Eland on a whim, and those were preceeded by some knives from a heretofore unknown company called "twosun" which I've been very pleasantly surprised with. Additionally, many of my higher-end purchases are spur-of-the-moment. I picked up a 0301 on the super super cheap off eBay and I've finally come to appreciate why so many people are fans of the 030X series. The thing is a tank, but carries so well...! I've also never really liked assisted knives, but this one really makes me question that. I also snatched up a Spyderco Vesuvius, which is a long-discontinued compression lock version of the Centofante 3.
And that's just a few of the things I've purchased on a whim. This week.
I think buying on a whim, while potentially very expensive, is probably the most enjoyable way for me to experience the knife world. I've handled and carried HUNDREDS of knives in the last few years, which is more than most people will in their entire lives. I'll bet I've handled more knives than most people who work in cutlery shops or work knife counters at sporting goods stores... And I'm indebted to this forum for the ability to do so without going broke.