I am in the process of doing the heads on my 2009 C6Z, I just received the AHP kit # 4 from UPS yesterday.
I got the base kit, coated and polished, but, used oe Ti intakes, new Ferrera exhaust valves, 16 pm guides and
machining. The only thing I added was new oe valve springs.
That was $4000.00 cdn including the core charge and freight. I will get back about $1700 cdn for the cores, so, net $ 2300 cdn.
Gm head gaskets, ARP bolt kit, exhaust manifold gaskets, xover vent plugs and Dexcool added $500.00 cdn.
Local labour will be about $1000.00
so total, about $3800.00, add maybe $200 freight back to AHP cores.
If you did all DIY, you could be $3000 all in.
Fact.
I have no issue doing reconditioned intakes, They are thoroughly inspected before reconditioning and there are no reported failures
that I could find from this process. AHP do 300 plus of these heads every year. not all done with recon valves, but many are.
I did a lot of research before going this route. My only goal was reliability, not performance improvement.
IMHO, the common denominator to C6Z head repairs, no matter who does them, is properly machined concentric valve guides and valve seats. This is more important than the specific parts selected. Again,my opinion.
You can easily add about $2-3000 doing these heads with new TiMoly intakes, Moldstar guides, high end springs etc.
That is not including porting or roller rockers either.
To me, not required unless you are tracking the car or adding a blower, or just have deep pockets and want the best.
And, yes if you take your car to a shop to have all this done, it is going to cost more, why won't it, doesn't mean they are crooks.
You can't make blanket statements about the cost of doing these heads as there are many options and price points available.
You need to compare apples to apples.