my friend recently bought a Toyota Hilux 2001, 2.7 petrol, which is running rough and we would like to know if anyone knows what diagnostic tool it needs. Is it possible to plug my laptop into the diagnostic port without spending 7grand?

You want a product called Autotap.
The website is autotap.com .
It is a usb based scantool for reading OBDII.
It runs about $199 with one enhanced manufacturer PID list.
I have owned it for several years,and is a great tool.
I've used it for both diagnosing vehicles at the dealership I work in (Ford) and tuning vehicles for performance enhancements (it does not tune,only scans).
They have a new "express diy" version out now that is simpler to use.
You must know what your looking at though,it is a great tool but you must still do the diagnosis.