1997 Toyota Tercel Repair or Replace Engine or Buy New Car

Earlier tonight, while I was driving on the highway, a smelled a faint burning scent and a minute afterwards, my car broke down. I pulled off to the side of the road, yet it took at least a minute (going down from 70 miles per hour) to get across the lanes of highway. After AAA towed the car back to my home, the guy took a look at it and told me I had no oil in my tank (mine and another's fault. Long story). He added two quarts of 30 oil, after which I started my car and drove very slowly around the block. It was not making as horrible a noise as it had on the highway, but it was still pretty bad.
I know the inside of my engine is probably wrecked terribly, which leaves me with the options of either repairing the engine, replacing it with a used engine, or buying a new car altogether and selling my own for whatever I may get for it or its parts. My questions are, what would you suggest I do and can you inform me on the possible prices for repairing or replacing the engine? If at all possible, I would like to keep the car, everything else in it works well and I get amazing gas mileage with it, but if it's not worth it then I would like to know sooner than later to do something about finding new transportation.
Thanks a bunch.