Well, 3.5 K doesn't really seem like too much to me. If she's as calm and good natured as you're thinking, I'd be willing to pay that. Hopefully all works out!
As for the canter thing, as Epona said, it may just be that the trainers didn't want her to canter because she's gaited. And I've been told that all 'true' gaited horses don't know how to canter without proper "Grooming" for it. I'm not sure of the latter is true, but I've been told that time and time again.
Good luck though!
Cheyenne, QH Paint Trail Mare. Happy Trails, Y'all! Twister, Appaloosa Barrel Horse. Turn 'n Burn! These 2 horses stole my Heart!