I just did this like a month ago.
I felt ripped off when I got the #3, "Protector A". I thought it was a gasket...
The #3 is just a roll of self adhesive weatherstripping...
Save yourself the money and just go buy some local.
Look: "Protector A" (this is actual protector A I had left over)
Just go to lowes or homedepot, and get some 5mm wide, 3mm thick, self adhesive weather stripping. (or buy larger and cut it to that)
You could probably also find 4 thin rubber washers that fit the bolts in the spoiler tightly and use those for "Protector B"'s.
I am sure it would cost less than the $36+shipping it cost me at subaruparts.com
P.S. If you need the spoiler nuts let me know, I have 4 spare ones here somewhere.
I bought new ones with the protectors, so I have the old ones. I would mail them to you for just postage, lol.