Q: Engine? New car? Greedy mechanics? What's the real deal?

Our car was bought used from a shop about a year ago. It completely shut down a few weeks back. We know the coolant system has issues, and just before it broke down, the windows rolled up slowly, the lights were dim, and the car made a weird clicking noise the night it completely shut off. We did take the car in a month prior, and they never mentioned engine problems. When we brought it in to Tires Plus again, the mechanic said we either needed to spend 2500 on repairing the engine or buy a new car. Previously, all I'd heard was the clicking sound. After the car was at the shop for two days, it now makes a gurgling noise when we drove it home. What's your take on this one? Thanks!