Suggest buying the real deal. I think CNC Drive can tell if it's a knock-off if you ever need help and have to post your machine profile.
Really, for $60 its cheap insurance. And CNC Drive folks are awesome with support - check out their forum. They are, frankly, the best vendor of anything I've ever purchased for prompt & meaningful support.
Also, you might consider upgrading to the ETH400 or ETH300. Not much more money, and lots more inputs plus faster kernel. The 300 is the ticket because it adds - among other things - two analog inputs for FRO and SRO so you can have grown-up knobs on your machine instead of fiddling with on-screen sliders like in Mach3 or UCCNC.
And I strongly suggest using UCCNC instead of Mach3 as your control software. Way better motion trajectory planner (smoother/faster even with the same machine) and it has many features Mach3 just can't do well. Like rigid tapping.