That's absolutely understandable about the autofire! I can make some adjustments to make it more clear it's an option. I don't think it needs to be automatic, though, as you can use either the mouse or the spacebar to get to the amount of points needed to buy it. It's available from the start as the first option in the shop.
And there was a bug with the King Cobra's 100 points threshold, which has been fixed now!
Thank you so much for the feedback!!! <3