A new set of engine bearings for the rod bearings and main engine bearings ranges in cost from $30.00 to $100.00 per set depending on the engine and number of bearings required.
Smaller engines with less cylinders will require less bearings so that would mean they would require less money to buy the engine bearings.
If you can replace the engine bearings yourself then you can do so within a day or so and only your time will be spent along with the cost of the engine bearings.
If you need a shop to replace the engine bearings then it can cost from $200.00 to $500.00 for the parts and labor and if you need more than just bearings such as new piston rings, seals etc then the cost can go up to $1,000.00 or more.
You'll need a new oil pan gasket as well as rear main seals and other seals to seal the engine back up once they remove the parts to get to the engine bearings.
So expect to pay between $500.00 to $1,500.00 to have a shop replace the engine bearings.
Sometimes it's better and cheaper to just find another good used engine or buy a new engine or a different car or vehicle.