If a button is lost or lock tab gets broken, you'll have to pretty much buy a new kit.  The parts are somewhat expensive, at least relatively to how basic they are.

Using these designs, you should be able to print almost identical items out of any material, in any color your heart desires.  Don't like that those ivory buttons and lock tabs become yellow and break easily?  — Print them out of carbon fiber-infused black filament without having to leave your yacht or RV!