Hi Trevor, Often with machines of this type, and 3D printers, there is a large Youtube community posting about the specific machines. If you search on youtube with the make and model you will likely find LOTS of good info about capabilities / good points / bad points before you buy.
One thing I have noticed about cnc routers at the low end of the cost scale is that the motors look like ordinary Johnson-style DC plain bearing units with an adapter collet chuck tacked on. The bearings in ordinary DC motors (intended for fans or small appliances) are not designed to take heavy side or end loads as they would see in cnc router cutting or milling. I don't think the bearings in these motors would last long, especially with plunge cuts / end loads since the thrust brgs are minimal if present at all in a lot of common DC motors.
If you can find a router with a belt drive to a separate spindle (preferably ball or roller bearing) then the motor will likely last far longer and the cuts will be cleaner too. With a separate spindle you might be able to rebuild / tune / improve it or get an upgraded one if problems occur and the youtube community responds. For 3D printers for example, there are many "hot rodding" performance improvement kits for various modules of the machines, shown and reviewed on youtube.