I only collect coins from my Garrison and detachments I belong to (FISD), but I have been given many from other Garrisons and I keep what is given to me. All told, I probably have about 15 or twenty.
You are on the right track. Asking questions and checking your measurements before making cuts is very smart. Good luck! I will be watching your build.
I am sorry to hear of your troubles. This is already an expensive endeavor, but to be treated like this and possibly lose money is unacceptable. I hope you find satisfaction.