Where can I find screws looking for my MacBook Pro 15" 2012?

Hello, recently when replacing optical drive, I had chewed up one screw and had to drill in order to pull it out. I am looking for 3.9 mm Phillips Screw. I'm looking for a screw in step 9 of this guide: MacBook Pro 15" Unibody Mid 2012 AirPort/Bluetooth Board Replacement

Also, I am missing one screw at the bottom of the case which is 3 mm Phillips screw. If someone could help me out where I could buy those without buying a bulk of screws what's ifixit is selling for $59.95, i just need two, if comes with little bit more than that, I'm fine with that. ifixit selling in bulk: MacBook Pro 15" Unibody (Mid 2010 - Mid 2012) Screw Set

Thank you