So...the GAP tool is not just an OBDII reader, it is also a programmer, typically for modern Rovers. It specifically allows you to mess about with all the many sensors on something like an LR3, like the suspension settings. However, if you just want a cheap scanner, they are plentiful. Some are plug in and are powered by the car when plugged in. Some are apps that run off your phone or tablet, and require a bluetooth or wifi based "dongle" that plugs into the OBDII port and transmit to the app on your device. A good example of that is
JScan (Chrysler/Jeep/Ram specific) or
Torque (android only).
Autel is a very reputable brand for OBDII scanners, and they range from $35 to $7000. I gave
this one to my daughter and its served her well on a Subaru, Mitsubishi Montero, and Honda CRV
Looks like Autel has
an app version with dongle also, but I have no experience with this.
Just a warning, some systems will have capability, like ABS functionality, but you have to "unlock" the capability with a paid subscription (ie, extra $$). So read the fine print.