I know it's a different model year, and perhaps would have better sales being full-detail, but from what I've seen you have to pay someone $20 to take one of the Hasegawa Polizei Beetles off your hands. I've seen them as cheap as $12.50 with no takers.
Possibly only feasible for the European market, where the Hasegawa cop bug is a stronger seller. OK, one could butcher the police parts from a Hasegawa for the Revell. In essence it's only the dome light and loudspeaker anyway.
Standard beetles will also make fine German, Austrian, or Swiss postman cars, if you're starved for ideas.
Now, where did you say they sell Hasegawa beetles for 12.50?