I had a 6m high performance rebuild a few years ago at a cost of about $2400. Subtract $600 for the forged pistons and probably about $450 for the head work and $100 for the ceramics and you come to about $1250 for the block work and gaskets. That did include fully balanced entire rotating assembly from flywheel to harmonic. I just did a very basic rebuild on a 5m block for about $650 but that did not include boring the cylinders, only crosshatch hone and new rings and reused the oil pump. Both cranks were std, just polish. I'm sure labor rates vary a bit from place to place but that probably represents the range you would be looking at from a minimum to a maximum depending on how much work is really needed. People telling you to expect much lower costs are probably used to thinking american v8s for which parts are cheaper and cores are so plentiful its common to just exchange (rebuilder gears up and does'em in batch to same spec rather than tooling for each engine in order it comes like the import shops have to do).