How much of the 50' is left - look at image 2 - your guess is as good as mine and I would guess about 2/3 or 34 feet
I was using it in my Epson Stylus Pro 4000 with no issues
Price: $75 includes shipping to any CONUS address in box shown in Image 3
Price for a new, full roll was $139.99 at ATLEX
Happy to provide online selling references from Fred Miranda or Ebay
Bob