Petrol isn't the issue it's the "what if's". My 3200 was generally very reliable but there was ALWAYS something that needed replacing, either at service times or unexpectedly. Parts that last a lifetime on mass produced cars appear to be "consumables" when you get into exotica territory. Wishbones, steering racks, throttle bodies, et al. Unless you are sure that you can replace worn out items as they are required you're simply going to be adding to the pool of very dodgy Maseratis out there. The fact that they are so inexpensive to buy is in my opinion the main reason that there are some dogs out there. When you're an old bugger like me (50+) insurance is no problem either - even if premiums are rising at an alarming rate.
Let's just hope that there are enough good's left out there when I do buy again.
Good luck with the sale. There must be someone out there who can take the running costs.