These are readily available, and in many cases a LOT less than that starting price for new boxed ones. If you google for them you will find several companies selling them.
They were used on a lot of other cars such as most of the 60s Triumph cars, so can be found second hand all over the place.
For those that are interested, you need three of these per car.
What made you go looking for those Robert ??
Cheers,
John.