Something that's not well-made or high quality is second-rate. If you buy a cheap second-rate car, you may end up spending a lot on repairs instead.
Second-rate things are mediocre, shabby, or inferior. A second-rate production of Hamlet won't be as well done as the Royal Shakespeare Company's performance in Stratford-upon-Avon. And a second-rate cup of coffee might need a lot more cream and sugar than a first-rate cup, but it will cost much less. The adjective second-rate was first used to describe ships, from the British Navy's official classification system.