It's safe to say that most cameras will have a life of around 200,000 shutter actuations. Consequently, most people are looking for second hand cameras that are around 50-60,000 actuations as a maximum. The fewer, the better.

How many actuations is too many?

Most entry-level DSLR cameras are only rated at 100,000 shutter actuations. Mid and high-end cameras have more durable shutters that are rated up to between 150,000 and 300,000 actuations.

How many shutter count is good?

On a life-time scale, an entry-level camera should only be expected to reach a shutter count of around 50,000, while a mid-level camera can reach 150,000, and a professional camera should be able to reach 300,000 or more.