Damn Dirty Ape I Love You
Even though this question is over 2 years old...
When rolling a 6 and moving again it is a new turn. Since the field on which you land determines what you can do (buy or build) you never have the option to choose between those two.
Hmmm. I don't see anywhere in the rules the bit about moving again if you roll a six. Is that in the US version of the game?