I know nothing about this seller, but did notice they just joined today.
I can say that the type of wheelchair offered is unlikely to suit the needs of a PALS for long.
This wheelchair does not have a "rehab" seat, meaning it cannot be adjusted to properly fit the patient. Also, it does not have power legrest, tilt, and recline that I find so essential.
As for price, I can say I purchased a used Permobil C350 (rear wheel drive) wheelchair with 36 miles on it for $800. I had to replace the seat back with one properly sized for me (they are designed so this is easy and pretty affordable) and install a headrest, but all the basic pieces were present and worked just fine.
The Permobil C350 is a far more capable wheelchair and far better suited to the needs of a PALS than the Jet Ultra 3.
I don't mean to suggest that folks should not consider a Jet 3 Ultra wheelchair if they think it will work for them. I just want to make sure anyone interested in it does their due diligence before thinking about purchasing it.