2002 Chrysler Sebring LXI 4dr. sedan V-6

Close to 110,000 mi. on my car. Suddenly started misfiring in cyl. 3. Mechanic informs diagnostic test reveals that the ring needs to be replaced, as it’s allowing oil to the plug. He states that I should replace entire engine, as replacing 1 ring would mean replacing each piston and all gaskets etc. Is this correct? If oil is getting in wouldn’t there be smoke of some type? I don’t really have over 2k for a new or rebuilt engine.