The cost of any part increases in proportion to the precision of its dimensional tolerance requirements, this is true of castings, as well as fabricated and machined parts.
While careful machining can achieve closer tolerances than available in an investment casting, a critical design view will often permit minor expansion of tolerances, undercuts,
blind holes, etc. to allow the higher production yields and lower piece costs possible with investment castings. If closer than cast tolerances are necessary, the machining required
on an investment casting will still be substantially less than on conventional cast or fabricated pieces.