Lulu is awesome, free, and open-source (so... triple awesome?). I've personally used it for a couple of years and I can definitely recommend it.
Unfortunately there have been 3 separate times that it seemed to completely forget its configuration and having to allow or deny every single connection all over again gets old pretty fast. Little Snitch also looks nicer and has a few more features, although nothing life changing.
With that said I just saw a decent discount and decided to share it. I'm not saying you should use one over the other or anything like that.
You are right to share this very good discount. And thanks for telling others your experience with Lulu. For me I never had this problem you described with Lulu. I tried Little Snitch in the past and I find it overwhelming. Alle those options, questions if you want to block something or not (yeah I know you can turn this off and let LS do all settings). Then I found Lulu (before I used RadioSilence app on my Mac) and this is a very easy free app, which can positioned between LS and RadioSilence. Happy with it since day one.