Nice to know there is a reason. It's a shame there is no budget (not bodged) alternative to a hugely expensive track/car. Maybe buy the track only and get on the lathe/mill!
There is always a bodge

This was done using a bent bit of curtain rail and the bow fitting from a Laser II.
It could however be turned into a budget method. If you make a curved track from either glass or carbon, sized so that a block can run along it in place of the crappy U bolt above, you have your track and slider.
It has to be very strongly fixed at each end as there is no support along the length or in the middle but it could be made to work
I think that for a budget build there is potential in bying an old boat like a 14 and stripping it for parts, for £1000-£1500 you should be able to get a 14 with loads of blocks and string, foils, potentially a carbon mast, pole and boom maybe even a road trailer. The Sails could be converted or you could probably get £200 selling them back to a budget 14 team.