Hi Phil
As Zen mentioned i have managed to arrange a few limited edition runs for various events and clubs - including Slotforum (50 SCX Cudas), NSCC (500 SCX Skodas & 50 Teamslot Toyota Celica), SlotrallyGB (50 Teamslot Lancia Stratos & 50 Teamslot Lancia Delta).
To be honest it can be really difficult, time consuming and frustrating.
The bigger manufacturers (Scalextric and SCX) will want a run of around 3000 - 5000 cars and then only if they can fit it into their schedules. It doesn't really make any difference if you are after plain untampoed car either. With Rob Smith i also managed to buy a number of plain white Scalextric Subaru's and IRL's (not directly from Hornby).
Smaller manufacturers are more flexible, but even then will only really help if they are directly involved in the event or championship.
To be fair, in recent years some of the Spanish companies (like Ninco) have been much more flexible for short runs (i guess due to the current financial situation).
Ultimately it comes down to how good a relationship you have with a manufacturer, how many you want, how much you are willing to pay and for what purpose.
I think the easiest, but less desirable option, is to buy a number of existing cars in bulk and have them tampo printed after market (like the recent NSCC swapmeet Scalextric Ferrari). From a collecting perspective these are not as popular but much much easier.
Any approach from an individual will be tricky, you really need a club, organisation, retailer or event behind you to back up your request.
Good luck!
