I would not recommend a Delphi knock-off.I agree. Something like a delphi copy is around £150 with a laptop. It will pay for itself no time.
I have one, but the knock-off interface is horrendously slow to the point of being unusable on some vehicles, plus the last I checked the software version was still the latest one before Delphi moved to security dongles, so was pretty much useless on anything after 2014 IIRC.
Although it was worth buying for all the adapter cables, which made a couple jobs at work easier.