This was fun! The upgrade system is a nice touch, although it could use some more balancing.
The spawn chances seem broken. Once I upgraded the gold spawn chance enough, the board would always fill up with gold and nothing else, allowing me to spam click every hole.
When the shop has enough items to make it scroll, the lowest item cannot be clicked. I would guess that there's a control in front of it blocking the input.
Aside from that, I enjoyed this. Great work, especially for only 4 days!