Depends
"Well south" of 200k is going to be some kind of trouble - probably engine trouble.
That's ok, if you want to repower. Indeed, its what you WANT TO FIND if you want to repower, because there's no point in paying for good machinery you're going to tear out, and while you'll get SOMETHING for the take-outs, its not the way to go.
You're way ahead of the game if you're going to do this sort of thing (repower) as a plan to find the boat that has blown up engines and get the seller to sell to you BEFORE he rebuilds them. That's difficult to do, because sellers KNOW that blown motors will whack $30k off the price of the boat in the bat of an eye, but they can get "joe and jim's rebuilds" to do cylinder kits (and nothing else) for about $10k - which means they POCKET $20k by doing it "on the cheap". Of course you then get the headaches and probably the wallet-ache that comes from that - the seller simply doesn't disclose anything, the survey comes up ok, but what wasn't done.... hmmmm... you don't know, do you?
The other "well south of 200k" deal you'll find on a mid-80s 45C is the boat that is part of a bankruptcy or some other situation (e.g. estate sale - the old sap who owned her kicked over from a heart attack and his widow has no interest in the boat)
The problem with those is that neglect is usually rampant through the systems, from electronics to the hull to bottom paint to running gear to the engines. Why? Because those situations don't arise overnight, and the maintenance budget (either in time, money or both) usually evaporates long before the final song is sung on the underlying problem.
If you want a 45C with 6V92s in good shape, expect the price to be right near the 200k mark, perhaps even a bit more if everything is up to snuff (e.g. reasonably new water heater, fridge, entertainment, electronics on the bridge, etc - and of course a newer and well-running genset and properly-operating mains.) If you want a boat with blown motors, you might get in the mid to mid-upper 100s, PROVIDED you can get it before the owner rebuilds the engines.
If they still run but are just smoking like hell, that's the deal you want - you can get home on what you've got at low cruise (run it at 1100ish - you'll only make 9-10 knots, but that's real easy on the engines and running gear), plan the repower, and have at it. Completely BLOWN engines make for a bigger problem unless the boat is in your backyard - dealing with a yard on a repower job that's 500+ miles away can be done, but its not ideal - ideally you want to be around when the work is being done so you can watch it.
The nice thing about the 45Cs is that there are a lot of them. I can tell you where all the good and bad points are - as with all boats, it has some service hassles, but there are no really bad nightmares - just some relatively minor challenges.
For the 90th percentile, Hatteras thought through service access and did a pretty darn good job. Compare the service access to routine things with pretty much any other make in this size, and you'll see immediately what I'm talking about.
I won't own a boat I can't work on without killing myself - that leads to too many things that don't get done when they should, and THAT brings Mr. Big Bill calling on my wallet.
Hatt ain't perfect in that regard, but they didn't do bad with the design on these boats.