Nothing wrong with a cheap MM but work with it a bit to understand it. By that I mean, test some sensors (the FSM has instructions on testing many sensors, what ohm range it should be at when hot, etc), because having an accurate ohm measurement is helpful. Many meters will not read something measuring 10-50 ohms correctly, they will just say it's zero ohms and therefore a short, but that same item measured on a quality meter will say whether it's 6 ohms or 8 ohms, giving you an accurate reading, which may or may not be needed/helpful.
I have a WaveTek meter I got as a gift, works very well, has the temperature probe (thermocouple), which is cool when someone asks how freaking cold it is outside while we're wheeling...well toss the wire out and we'll see...
If you want something to measure AC/DC current accurately you can get clamp meters which connect to a MM, they actually put out a voltage to the MM, so you read amps by reading what voltage the clamp meter puts out...the cool part is that clamp meter can be plugged into any MM, the bad part is they are not cheap, AC current meters are alot cheaper than DC models...and yes a normal MM can measure current up to 10-20 amps by running it through a known-resistence wire and measuring voltage drop across the wire (all internal to the MM, but if you take it apart that's what you'll see), which is fairly accurate, but does impact the circuit you're measuring somewhat, more than a current clamp, which doesn't even physically touch the wire.
The reason I mention using the meter before just stashing it in the toolbox is I have seen atleast a few harbor freight meters which the leads were bad on, didn't even connect internally, so if you pulled it out of the box and started using it without knowing the wires were bad, you'd come to some odd conclusions about your vehicle..
Good Luck...
