I found an entire box full of those corner seals, the problem is they are only for one side. I couldn't find any for the other side, and I looked through the entire box. If I'm looking at the receipt right they were $6 each. Listed as door corner weather seal. I know someone used to sell them online, but it was for one side only, I would assume it was VPW.
I bought 4 thinking I could somehow take one, and make a reverse version of it.