You need 501 cowbells instead of 500 to buy an extra milkbottle

[toams]

This condition:
if (price < global.saved_cowbells):
is only true if you have 501 or more cowbells.
changing this in something like
if (global.saved_cowbells >= price):
will fix this

(I'm to lazy to clone and figure out how to build to test this fix myself sorry 😃 )