I appreciate the kind words on balancing, especially because it is something I struggled with quite a bit honestly!
I had also found in play testing that the one less spin per shop was definitely the best upgrade, although 2x your points can also go crazy for getting high scores, especially if you get it more than once. I actually already have some plans to address some of this in the post-jam update!
I'm a bit puzzled on your issues with the '2x on nothing" and "15 points per unused spin" upgrades, as they should work as described. Not sure if I just did a bad job describing them, you encountered a bug, or some combination of the two, haha.
I will say, both of those are also very difficult to see the effects of because there is no indicator your get the extra points besides just seeing the points go up (another thing that really needs some.work post-jam). The 15 points one is actually not even added until after the little ending message screen pops up, so it can be very difficult to see it triggering.
Either way, I'll mess around with them and see if I can figure what happened. It's too bad because those upgrades can be pretty fun in my opinion. Especially if you take them multiple times, you can get some crazy points.
Sorry for the giant comment... Thanks so much for taking the time to play and leave such amazing feedback!