Ready to use Presets for Lightroom are handy, but use them as a starting point. Try them on a number of RAW images, see how you like the results, take a look at the settings and see how those settings make the image look the way it does. Once you've done that, then you can make your tweaks from there.
If all you do is download a preset and apply it to every image without tweaking and learning how it works, you're no better than someone who just snaps a photo on their iPhone and applies a filter in Instagram.
$75 is a lot of money for presets. You'd be better served spending $75 on training to learn how to create your own style.
I've never paid for any Lightroom Presets, but I've downloaded plenty, tried them and now have created my own set that I use on my images.