We had Xerox WorkCentre 7335 under the contract once, 11c per page any size, no min, no max, everything covered bumper to bumper, would be less if I'd committed to some quantity, like 5K or 10K per month. Xerox is greediest one of all. From what I learned hanging out on few printing forums, industry's average 6-8 cents per page any size for units of this grade. It is usually on a higher side if you did not buy the machine from them or you trying to enroll used machine, logically thinking - if you didn't give them a chance to load you up with few grand per month lease, they tend to be a little less forthcoming/flexible on "per click" prices. When we sell used B/W machines locally and take them under the service service contract we charge 1c per page on LTR, if customer go shop for new, they may get 0.7-0.8 cents. It it never to really rare that I hear someone saying "Hey that $0.002 is a deal breaker". In your situation, if you can/should push for 8c per side of max size, it is on higher side of an average but nothing extraordinary. Sure if you take on Xerox IGen4 most likely it will be less, add acquisition cost (lease or buy) and numbers will be insane unless you have insane print volume. Duplex is double, sure, it is just another page for the machine to image, realistically, what is behind you being surprized? What would be the difference for the machine between imaging another page or flipping the one that still inside?
Are you talking to Konica Minolta itself? You're not the business office and it is not a office copier, most of these run max size than cut in any print shop, why do they even start a conversation with LTR size click? It, most likely, will be a tiny fraction of what you will be printing... Do they know that you are the printer? Do they know that you asking about something that is not a office Toypier?
Try calling KM 1-800 number directly. Tell them that you are printer (which undermines a quantity and that you'd be printing 12x18 size mostly) see what they say.
Another thing to expect - nobody will give a contract on used machine blindly, they will send a tech to check it, make sure that is OK to start with. If/when you go for it, before you pay for the machine, get a S/N, meter reading, supplies life printout from the seller, show it to your dealer and ask what can you expect as a "Roll on" expense (it is about the same as your car insurer will pass the car trough inspection before issuing a full collision policy with difference that they will mark a damaged spots if any and let you go where your dealer will charge you to fix the issues because in case of a car they responsible pretty much for appearances and Copier dealer responsible for mechanical performance) I imagine if machine of your choice will have Drums, fuser, etc less than some percentage of life left, they will insist that they'd be replaced upfront at your expense obviously - that may not look pretty so please figure this part out before spending anything. Buy smallest print count you can afford, you still will save tenth of thousands VS new and save huge on Service Contracts Enrollment bill.
To sum it up, no, the prices you were given not out of line but yes kinda expensive-ish, depend what did you tell them... Everything is good or bad, cheap or expensive, hot or cold is in comparesment..
If you consider 4c per LTR to be expensive, what is not? Do you know someone who pays 2? Even if yes (which I believe is hardly possible with machines of this size, Is his situation same as yours? i.e. rolling under a used machine with same quantity commitment? I would imagine it would have a huge difference if you'd try to enroll used machine with 3 million clicks and machine with 300,000 clicks as well.
I own Copier service company and a Printshop, if it would not be for constant equipment flow, I'd put my Konica Minolta Bizhub c65HC on contract for 8c per max size, hell yeah, we sell 30c to 45 c per LTR retail, 15 to 25 wholesale, double all that for 11x17, 80c for 12x18 on text, $1 for Covers, double all that for duplex, even if some may say 8c per click is expensive-ish, I could not care less. I make money, let someone who would theoretically support it make some as well and let me run the business VS fixing my own printers.