Be aware to use a QUALIFIED consultant. Make sure the contract makes em responsible for what he does for you (good luck with that one), make sure its a person or company that is able to meet his responsibility.
should I decide to charter out the aircraft when not being used for personal use.
There are many traps in what you want to do. If you think you are done by fulfilling the requirements right now, then you might be waken up rudely one day. Eurocontrol are constantly coming up with new requirements. Those are smaller things (such as a new software in TCAS, mind you that is 25.000USD for our airplane, 2007 built A/C) and some are big issues, such as CPDLC. (for which we have an exemption for the time being, but the manufacturer isn´t able to tell us what will happen, if they are able to implement it or not)
The newer the airplane and especially the avionics are, the easier (thus usually less expensive) one can handle these things. Bear in mind that a 2013 aircraft could be equipped with an avionics suite way older in design.
Oversight of your airplane in a operation might be a problem, I have seen more than one owner being deceived by dubious operators.
If you really want to charter out, speak to the potential operator first. Its usally way easier (aka cheaper) to integrate a type that already is in the fleet than to add a new one. A good operator canat least tell what question to put forward to a consultant.
A major, if not biggest part of the cost, is maintenance. There are huge differences in pricing even for the same types, let alone between different types. MSG-3 maintenance plans tend to be more flexible an dcheaper than the old ones. I have just made a comparison between two mx providers and our current one saves us roughly 15% annually compared to the other who said his prices would be highly competetive. Think how much one would need to charter out to get 10.000€/year back if one would make a profit of 200€/hrs -> thats 50 hours just for that and these 50 hrs do require maintenance as well...
I could go on and on, but it boils down to:
know what you want/need to do FIRST, then you will be able get the right airplane for the lowest possible cost. Be as honest to yourself in this process as possible. IF you
need to make money by chartering out, forget it. Way to many idle airframes around these days.
Put something on top of every estimate you ever get, 10-20%, and you wont be surprised by sudden pricechanges.
I´m not a consultant, btw.