Your dealer might just give you some. Discount Tire ripped off one of my flaps (and left it just hanging by one screw thinking I wouldn't notice it !!!). They had broken the plastic christmas-tree and lost one of the screws. Long story short, the dealer just gave me a new plastic piece and a few extra screws. Give that a try.
You can try the dealer, but if the holes are stripped replacements wont help. I had flaps put on mine before taking delivery. I dorve the car home and checked the flaps since dealer installs are hit and miss. I found that the right front had 2 screws that were stripped - they obviously didn't check their own work. I had a box of misc. bolts / nuts / washers and was able to find two black ones of slightly larger diameter. By screwing them in, the stripped holes were re-tapped and they seem to be holding just fine.
My Vibe: 2004 Base, Fusion Orange, Mono, ABS, Power.16" Alloys, Factory Alarm, Side Air Bags. Cargo Box