Priced individually. The CIS fuel injectors are a pretty durable item, but years and years of high heat, varying fuel quality and general wear and tear can create a number of problems. If your Mk1 has various dead miss problems at idle or partial load, or perhaps has starting problems, a leaky injector could be the culprit. CIS fuel systems rely on very high pressure to open the injectors, when the injectors are faulty you will not make maximum power, plus you'll have terrible fuel mileage and more. Use qulaity Bosch injectors and get your CIS Mk1 back in the hunt!
Please note, this part is for the later style CIS Mk1 cars, such as the GTI, that had air shrouded injectors. You'll know if your car has air shrouds if it has a metal or sometimes plastic port on the back of the head. Always buy new injector o-rings when you install new injectors!
The CIS fuel system is a great set up for naturally aspirated motors, and when everything is up to spec, it is dead reliable and excellent for performance. The problem is when vacuum leaks and faulty fueling parts are not replaced it will quickly have problems, leading to hard starts, inconsistent performance and unreliable running. Keep your early car original, and reliable, with quality new fuel parts. Most are from Bosch or are OEM VW.