alot of this depends on the OP level of skills.
if he feels confident enough to rebuild a buick properly it wont cost tooooo much since the labor is generally a big part of the equasion.
but if feels that the time spent to mic the bearings, double check pushrods, clean up oil galleys, Earls front cover mods etc etc then it will quickly rise in price having to depend on others to do the work.
farmed out = expensive.
self done work = not too expensive.