I just watched this video where they demonstrate a couple of low cost probes, including the PP150. The video shows the SA at 10dB/div and the probe is all over the place. There appears to be a few problems with their test setup. The long ground lead for example.
For a comparison, I used my 3589A to sweep the PP150 from 1KHz to 150MHz, 0.2dB/div, with the probe grounded at the tip.
I am still very impressed with these $9 probes.