In QLD changing the exterior color of a building has been considered an alteration to common property and so requires a SR (an interpretation I think is crazy).
Agreeing to a motion without any quotes whatsoever is giving the people who proposed this motion (EC?) virtually a blank cheque to do whatever they like and all owners will have to foot the bill.
At the very least at the AGM a max spending limit should be added to the motion to limit your expenditure. If cost (or quote or estimate) goes beyond this limit EC have to come back to owners for further approval.
Ideally you should have at least 2 detailed quotes showing what is going to be done and the cost before you vote on the item and you should advise everybody before the AGM to vote AGAINST the motion unless quotes are supplied.