electronics experts

Hi guys You know them kids battery operated toys you get where you press a button and it kicks out the same annoying music... Is there any way of changing this? My boy has a little toy Maserati car which when he presses the horn blurts out some weird ass music tone. I wanted to replace it...

I am looking for something that will do the following. A single short beep every 90 seconds when it has a 12volt dc feed present. has to be low current. Whats the best and cheapest way to achieve this. Maybe @Spectre might have some thoughts ;)