I am going to list a bunch of negatives, know that i do not do this because I dislike what you made, but because I would like to see where it could go.
The sound is a bit grating, a deeper or less singular sound may be better.
It may be good if coin movement, collection and amount had different sounds. At high magnet levels, the sources may need to "bunch" into premade multi-coin SFX.
The upgrades are too steep between buy-cycles to have any thought to them, you either get them or you dont, there is no decision aside from that.
The prior problem means I cannot really experiment with big collection radii, strong magnets and then respec, there is just having the upgrades and not having them.
The way the upgrades are laid out also at first implies related upgrades will be in each branch, but they scatter more randomly. This made me believe that a bunch of upgrades would only apply to the auto-collecter for a while.
This could easily have an infinite mode by hue-shifting coins.