Final answer:
The micro-purchase threshold for construction is not specified in the given information.
Step-by-step explanation:
The micro-purchase threshold for construction is not explicitly defined in the given information.
The information provided discusses the theoretical willingness of townspeople to spend up to $3 million for the passage of a tax, but it does not specify the threshold for construction projects. Therefore, without further information, it is not possible to determine the micro-purchase threshold for construction.