I have one - I'm not offering it for sale - just a couple of notes about it.
1. My plate came from a 301. As long as it's the complete plate - including the finger retaining things (an off night, can't recall the name and too lazy to hobble to the basement and look it up) - it should be a direct swap. This may open some options for used plates for you.
2. I went back to using my non-marked plate because I found when I used a 1/4" foot with the blade, the blade would pop in and out of the marking on the plate for 1/4" and cause a really wonky 1/4" seam. If you sew with a 1/4" foot with the blade maybe try first for a bit and see if you even like the combination.
It's just an expensive accessory that sits in my case now.