Hey Bill,
Found the one you're looking at.
What would you be using it for? Personally, I think it's pretty small. I don't have the specs on the HPX, but this can't be any more than what your cargo box holds.
A couple things that I see that would make me not consider this one.
Too small (volume & weight capacity).
Too low (can't see it to back up).
Tongue too short (can't tell for sure but it looks like it's so short that it would be very difficult to back this trailer up. Trailer might also hit tire on sharp turn)
Personally, I would take the path closer to what chief5 has mentioned. A general purpose trailer can be gotten most anywhere at a reasonable price (HD, Lowes...). TSC has a 4x6 trailer that's probably close in price to the ATV one you mentioned but can haul twice the weight and even at 4x6, almost twice the volume.
As soon as they put the word "ATV" next to a trailer, the price always seems to double.
Brian