So I guess that means something small.
If its a situation where you absolutely can't get caught, something small and cheap might be ideal. An older Ruger, S&W, Colt, or Dan Wesson revolver might be appropriate in that case. They're all functionally good. And they are all very nice if in good condition. But if you find one with plenty of holster wear and some external scratches that is still functionally good, it will be a fine weapon that will last for years.
It doesn't hurt to have a throwaway weapon, provided you don't get caught "throwing away".