I have bought a portable Autel MaxiScan MS509 for €42 off
ebay (including shipping).
Nice scanner. It can read approx. 20 parameter values from the ECU.
The nice thing about it is that when an engine error is recorded, it also records associated parameter values (at exactly the same time the error occurred) in order to be able to identify the problem better afterwards.
The scanner connects also to a PC for software updates through internet.