Here are some prices on low end forged parts: Callies makes 5 different forged crankshafts with a significant price difference between top and bottom - the same applies to the other parts. Callies cranks can be found for $800+, Eagle rods $500.00+ and Mahle pistons about $600.00+. Lots and lots of smaller parts will be involved in the build such as head bolts, rings, bearings and gaskets; figure $500.00. Labor is a big factor, the engine has to be out of the car to do it right. The bores should be precision honed and the rotating assembly balanced. Might as well go with a cam upgrade and head work too. A first class job will run much more than 4K.