Thank you for playing! If you have a lab and click at the potato button it has a chance of changing its shape (the only mutation we managed to implement in time). But yeah it has near to none mutation related aspects implemented.
In relation to being able to buy with 10 less potatos that prices, I think its because the balance label actually tweens to the new updated potato balance values, so what we see is a little bit delayed from actual current balance. Maybe in future we can use the current tween value to limit purchases instead of the unprocessed value. Thanks for addressing it!