Is it cheaper to replace the entire engine or to change the crankshaft and camshaft sensors?

Might I ask what the original problem is? It's very rare for both cam and crank sensors to fail at the same time, especially if it still runs.
As for the question of engine replacement versus repairs, it depends on the repairs but normally you can expect an engine replacement to be far more expensive than repairs. As an example, the current price on a long block remanufactured engine for that car is $3,400.00 plus 12 hours of labor not including fighting with rust.

Okay, the codes you have are circuit codes, basically saying that both sensors are turning on and off at random. I suspect that if you can read the freeze frame data for each code you will find they occur at the same time. I suspect the issue in both is a bad ground as they share that between them. Attached is the wiring for those sensors and you can see the common grounds. They also share common power but that also powers the injectors, and you don't show misfire or related codes for those. As those two seem to be the ones with an issue I would probably start by unplugging them both and checking for any corrosion in the connectors. Then if you find nothing, I would be tempted to just run a pair of new ground to the sensors. They are the brown wires with yellow stripes, and you could simply remove the insulation on the wiring on the sensor side of the connector, in the event that the connector is the issue or one farther toward the ECM, then simply connect a jumper wire there, solder and seal it in place and connect the other ends to a good ground nearby.
Then clear the codes. Next go to the power splice connection that has the multiple yellow with black and black wires, unplug it and plug it back together. Now drive it and see if the codes return. If they, don't you have a repair.