I mean, I suppose that depends on how you're defining "overhead" cost? To sequence a human genome, you _need_ to purchase a ~$700 reagent kit from Illumina to plop into your HiSeq and a ~$300 library prep kit -- are these overhead? I wouldn't call them overhead, and this fixed-cost hasn't really changed for 5+ years.

Those two costs are what makeup the $1000/human genome stat, we don't factor in the human and consumables components