depends on who where and which brand u get. ive seen sum kits go for as low as $2 k like u say with the turbo, manifold, IC , piggyback EMS and pipes and thats it, i wouldnt call that a good kit, u run the risk at that price.

a 6K to 9K ive seen that still dont come with INJ FP and a stand alone EMS

the 9K to 12K was what i paid cos it was a 1 off production that peak boost did for me. as theres only 2 company that make em for my car and they both had shitty manifolds and small turbos.
i got the works done at a drive in and out price inc tuning and GB work and it would have cost less if i went smaller turbo. Aslo my prices build was when the dollar crashed in the US so that also affected my price.

but yeah the more common D series should be alot cheaper by say 2k as a drive in drive out package.