A lot of people debadge their cars to give them a "clean" look. Some manufacturers put minimal badging on their models for the same reason. Some people put badges on their cars that don't belong to mislead others into thinking they're something they are not.

I've always pit an extra "Diesel" badge on my cars to let following drivers know that the car can be slow up hills etc so they don't think I'm deliberately dragging my heels (it also explains a little extra smoke if the following driver happens to be a member of the Constabulary). And anyway.... I'm proud of owning a diesel.

Even the "TDI" badge on my Golf 5 is a little obscure to a lot of drivers and although it can show a clean pair of heels to most other cars in it's class (and above) I'm happy to publicise the fact that it's an oil burner

Badges are plentiful on overseas ebay sites. Try searching for "emblems" and decals" too.