HI, does anybody know where to get a replacement for HDB window flush bolt, used in the aluminium casement windows? They are greyish plastic and have a metal piece/bolt sticking out to lock down the window on top and bottom. With wear and tear, the metal piece tends to break out from the plastic casing. I saw a brand called Lock Plus, each system costs $17+, quite steep considering that stainless steel ones can be less than $10. Anybody knows where to get cheaper ones or alternative solution?