I have the 830 that I bought new about 5 yrs ago. It was $1100.
It is great and I love the auto foot. No lever or knee use just push the petal and it auto lowers the foot. When in needle down it will auto raise the foot just enough for easy turning your fabric or chain pieceing.
The fancy stitchs I still havent figured out how to set them up, too complicated.
I bought extra feet like 1/4 in but do not use them now. You have a setting for 1/4 in but it is too big so I still have to adjust the needle a little.
No repairs but do have it serviced about once a yr.
It measures 10 inchs for throat space and that is really nice.
My only complaint is the head is so low where the needle is that it is hard to fit your hand in there to do anything.
I had to buy an extra large table for it to sit flush with the table top as it is a big machine. The Bertha was the cheapest and has a nice large area for quilting. It is 7 feet long and has a drop down extension on the back. Takes up alot of room but holds the quilt up nicely.