I've found that good remanned heads for my LB7 run $1,200-1,400 from a shop I trust, ready to run. That includes surfacing, recess the valves as needed, pressure test, valve guides as needed, seals, etc. I imagine LLY heads would be very similar.
My brother and I were talking about putting L5P heads on his LB7, but when you add up the various required hardware, it is cheaper to just stick with reman heads, even though the bare L5P castings are shockingly cheap.
I have Wagler aluminum heads on my truck, and the total cost of ownership has actually been quite competitive. If you are reusing your stock valves and springs, grab their castings and bolt it all together. I went through a few SoCal Stage 1 LB7 heads, and even though the SoCal heads were "cheaper", by the time I add in the 3 sets of head gaskets, fludis, and incidentals, the Waglers were cheaper, ignoring labor! I suspect this person you're asking for will be doing their own labor, but doing it once sure beats doing it twice.
I would strongly suggest getting the Wagler castings if possible, and using your stock valves/springs to keep costs reasonable. They are a very well designed casting, and much stronger than stock Duramax heads, especially if you port a stock head. Plus, they flow quite well, even as-cast.
That said, it is unclear if Wagler is still making their aluminum castings anymore. I can't find anyone claiming they are in stock, or even the Brodix branded ones. It might be worth a phone call to Wagler to see.
