Since the tangent is more interesting to me personally:
I don't have access to very many detailed budgets, but taking a tiny fraction of generic ME offices and looking at their budgets vs autopsies only -- they ranged from about $2400 to about $5300 per autopsy, with the average probably about in that mid range of $3500~$4000'ish. But that's a misleading number, because ME offices do more than just pay pathologists to do autopsies. In addition to costs an average hospital-autopsy would normally incur (pathologist, tech/PA/deiner, facility, supplies, and histologic slides; only a few will do toxicology, though more "private" autopsy services will do so), ME offices also generally pay for forensic investigators, secretarial and administrative staff, photography, x-ray equipment, transport of bodies from scenes, time for pathologists to deal with the court system, and cost of investigating cases which either don't fall under ME jurisdiction or only get either an external inspection or a partial autopsy -- among other things, some of which vary by local preference or statute. Of course, they get to consolidate expenses and focus their employees on related tasks, as opposed to hospital/private surg path staff whose primary responsibilities (by volume) are elsewhere.
That said, I pretty much agree with mlw that most pathologists who charge separately for private autopsies do so in roughly that $2-3k range, up to around $5k, unless you're talking about the rare big names. By contract or prior agreement that may or may not include providing anything beyond an autopsy report +/- histology or certain laboratory/tox studies -- much of the time a pathologist (primarily talking about someone working as a forensic pathologist, even if not boarded as such) also charges hourly for almost anything beyond that, such as testimony or review of records/reports from someone else. The hourly rate is also pretty variable, but currently seems to usually be in roughly the $300-$450 range and accounts for some of that "extra" cost ME offices generally include in their annual budget.
In the end, the salary of an average FP broken down solely by autopsy numbers is probably in that $550/autopsy range -- most seem to do somewhere between 250 and 300 autopsies per year, depending -- with the rest going to other, obviously not insignificant, costs.