I saw those, I was going to buy one but I wasn't too clear with the "comes with both parts of the zip". Put me off.
I found a local interior trimmer that replaced the screen for me. I removed the rear panel and he fitted a new one in for £40.
Removing and refitting the panel is easy enough, lift up the rear section of the roof and you'll see a row of torx screws on the bottom of the roof frame. Be careful as they are easily rounded off. Then you pull it from the velcro and unzip it at the top, remove 2 elastic straps (held on with a popper thingy) and it's out. Pretty easy job to do.
The thing is, if the screen supplied on ebay doesn't mesh with the zip on the car, what do you do then, mess about sewing in a new zip? Might fit fine though.