Yes, gutter guards absolutely do work, and are ultimately worth the investment. But you've put your finger on a big problem in the gutter industry: Cost (as well as sales tactics. I'll get to that in a moment). The majority of gutter guards are grossly overpriced. The challenge is finding a product that works well at a lower price point. As far as Raindrop gutter guards goe, we have no experience with this specific brand. Give their reviews a careful look; they might be worth giving a shot. I suggest testing it on one section of gutter, ideally under a tree, to observe how the guard works before committing to any brand for your entire house.
My main concern about the gutter industry is its sales tactics. I've found gutter guard sales teams and reps will do anything to get in your door with their often overpriced product. Don't be pressured by gutter guard salespeople trying to get you to commit to an expensive product, because there are absolutely cheaper options out there. Home Depot has a wide variety of gutter guard systems that are both solid and perforated. It's definitely worth trying some out, especially since they're so inexpensive versus professionally installed versions.