I have mine from Flexispot.de and I absolutely love it. Already 3 years that I have it, I believe I got a good deal. I stand maybe like 10% of the time but still I think my body and my back is thanking me for this.
I don't stand a lot, but it is nice if I wake up and my back is sore. Also gives me better adjustability with the office chair, lets me set the height just right.