Hi Alex,
As far as I am concerned it isn't a syndicate. It is Jon's car. If Jon decides that he wants to make a seat available in his car on a "Pay per Drive" basis that is all we need to know.
Jon decides what he wants to charge based on the value/risk in respect of the car, consumables, wear & tear, entry fees, staff costs, supply & demand etc. We either accept those costs, pay up and drive, or we don't.
As you have already indicated (and I know from experience) motor racing is far from cheap. Once the real costs are established I don't think people will be quite as enthusiastic. Obviously, if Jon decides he is going to offset some of the real costs in respect of labour etc against the promotion of his business that is a commercial decision on his part. With due respects to many on this forum, I don't think they/we could afford the real cost - if we could we would be doing it already and probably wouldn't own 944's.
The seat obviously has a value and that is a straight financial agreement between The Driver and Jon. If a driver is able to negotiate a reduced rate through providing expertise, services or parts to offset a proportion of his fee, that is between Jon and the individual. This has nothing to do with any other driver who may wish to pay for a seat.
How simple is that?
Obviously, in a multi driver event - such as the 24hrs - then clarification of the agreement needs to be established. Do "The Drivers" only pay if they get to drive? Do they pay an "All Risk" fee where they loose their payment if Driver One has an attack of the Ayrton Senna's and smashes up the ride on the first lap? Is there some sort if mid ground where everyone bears some risk?
How much is a seat worth? Well in last years 24 hr, teams were selling seats at IRO £6K. There is a 24hr event at Spa purely on a Pay per Drive basis. All the cars are identical. IIRC one car, for a team of your picking, was £14K. .'. £3.5K each for a team of four.
Like I said....it is up to Jon.