my unexpert take on this is that if you want to measure voltage at 120 and below, AC and DC, most meters even inexpensive will be quite accurate, do fine and should be reasonably safe. If you go higher voltage then that, then checking out carefully the cat ratings become important and even essential as you go higher, your life may be on the line. For 12V DC in particular, there is little or no safety issue I think, and I will not hesitate to use my freebie HF meter if handy (see another thread here for accuracy tests of that one). For truck applications, with the possible exception of parasitic drain measurements, accuracy is usually not critical and is often mostly voltage anyway.
For current, the inaccuracies can be much larger. For very small currents, in the way sub 1A range, as in 10 to 100 mA, the errors may be large with inexpensive meters. Naturally, resistance errors will also be commensurately large. Current errors with cheap clampmeters can also be very large in that range.
Basically, I think that for the average DIY or homeowner, accuracy is not important and an inexpensive unit will do fine. You want to know if there is voltage or not, basically, that's it usually. So accuracy does not matter much at all for that objective. Now, if you start to dabble into more specialized stuff, like working with batteries, solar, checking motors and all, it's a different story, and then you may need to spend more $$ for accuracy or specialized features.
As to the Flukes -I have several, old and new- I suspect that the quality has taken a nose dive in recent years and that the company may be coasting on their earlier reputation. Check where they are made now. I will say, though, that the old ones were good. I have one that must be well over 20 years old, maybe 30, and it looks and functions like new. No plastic falling apart, nothing breaking from age. Fully functional. Perfect. So, an older used one may well be much better than a new one in fact (if treated right).
