Dev, with only 100 downloads and only 50 reviews, a good idea would be to emulate the practices of bigger devs. I.E. I just downloaded this and Play Store says there's an update. I read up on the app before deciding to download such a new app, sale or no sale. I'm the demographic you want, older with a good job and likely to spend $ on apps I think are worthwhile. (btw, the sale will worki for you, give it time, it was a good business decision.) I wouldn't have even noticed you without that sale section popping up. I came to see what the update was about and there's ZERO info. So, new app, very little reviews by, probably mostly kids, and no info on updates. You see what I'm saying? I haven't even tried the app yet.
It's ok but cool idea