I could find you a complete donor R5 turbo for around £500 possibly less, but cant garantee the condition of the engine. But that will give you brakes, loom, intercooler, all the pipe work, drive shafts, turbo, ecu.. etc...
When you buy an engine seperate from the car, its very unlikely to come with a turbo, sometimes wont include the manifolds, definatly not the ecu, so getting a donor car is a must.