Private plane charter costs may come as some surprise to you if you have never used a charter service before, but you must take into account the costs that the company have to meet to offer a private plane charter service, and weigh that up against the benefits to you as the user when compared to flying via commercial airlines with hundreds of other people.
This is an exclusive service, so the costs that are normally borne by a whole plane full of people are falling to you and your party whatever the size. This will be a much smaller aircraft so the actual running costs are going to be lower; however, there is still the cost of the pilot to be covered and any staff that are used at any point. It is lovely to drive your car onto the runway and load your bags straight from the boot on to the plane, but the service personnel that do this for you certainly are not going to be working for free. Private plane charter costs do vary, and there are many smaller companies that have lower overheads that some of the larger charter companies that can save you even more money. In terms of service it may not be quite as polished and exclusive, but again it depends on how much you are prepared to spend and whether a first class lounge service on the flight is important, or if you just need the flexibility of charter flights but do not need the one to one silver service.
There are many small private pilots who are happy to be chartered for flights, but this is just a plane service. There will not be any fancy foods offered, just a seat in a small aircraft that can taxi you personally to your destination of choice without frills but with the simple purpose of getting from A to B on your terms. The bottom line is you can save money, but you will lose on finishing touches. Companies cannot be expected to give away their services. Ultimately the decision is yours.