Assuming you're talking about the 300E and assuming it has the M103 engine, it's not a very difficult job to replace the fan bearing. Do a search on 'M103 serpentine belt' or '300E serpentine belt' for 90% of the steps.

The fan bearing is part of an assembly that bolts to the front part of the engine. FastLane has the fan clutch bearing bracket for ~$105... if that's the right part. The price seems right.

You might have to disconnect a small coolant tube for proper access to the bolts that hold the assembly in place. There won't be a lot of coolant loss but you should probably replace the o-ring if you disconnect the tube.

Sixto
91 300SE
87 300SDL
81 300SD