[oldeboo]

Well certainly a few factors at play:
-It's a common practice to not properly call this a WST as it should be as mentioned above
-You're looking at a card that has a POP of 10 in the PSA report and 2 in SGC with none higher
-PSA typically gets much higher prices I've heard
-More registry set builders in PSA holders
-If you're putting together a PSA 8 registry set you want high eye appeal cards
-Extremely popular set to put together with a lot of money in the higher end
-A wildcard could be a descendent or something unique like that
-Someone likely had to have the PSA one at any cost, literally. Often, that's all it takes. The buyer wasn't going to lose it for any price based on some of the factors above. I'm sure the buyer would have had absolutely no issue bidding 20-30k if that's what it took.

Is any Dave Harris card worth 10k+? Meh, I guess to at least one person it is and another thought it was worth about the same.

I think WSTs are neat and tell a story of the process, but not at the high end grades for set builders.