Lightroom presets are a highly popular way to edit photos or to (try) to emulate the look of a photographer you admire, but they're not always all they're cracked up to be. This great video examines why you should think twice before resorting to buying Lightroom presets.
Coming to you from Evan Ranft, this great video talks about Lightroom presets and why they're not a one-click solution to editing your photos. The simple truth is that photo edits are relative: they all depend on the lighting, exposure, color content, and more of the original photo, and thus, there is no absolute adjustment that works universally across all photos. As you'll notice in the video, Ranft has to apply the preset and then evaluate each parameter and adjust it to properly fit the photo he's working on. The adjustments are enough work that personally, I think it would be better to just dial in the look from scratch. It also takes a refined eye that you need to spend a lot of time developing to make these adjustments; if you've put in that time, you'd probably rather make your own presets than buy someone else's. That's not to say presets don't have a place, but think about whether your time and money would be better spent developing your skills before you purchase them.