MY POINT: You don't have to lie to people. There are 35 Performers for sale for every SP2P. That makes them rare.
They were designed for maximum fuel economy. Now maybe it's your opinion that they don't work, but that's what they were DESIGNED for. So it's a rare intake manifold designed for fuel economy. There isn't a lie in that sentence. There are actually s ome folks out there who are looking for the "ultimate" fuel economy intake and they may think that the SP2P is the Holy Grail. Now it isn't lying if you don't tell them they're wrong, everyone has the right to his own opinion, after all. I've seen them sell on the 'bay for $70 - $90 if they were presented right. That's a lot more than scrap, $15 or so.
So clean them up and get them out of your garages.
Shoot, the Model 4360 Holley 450s are going for $50 and up used but clean! Two years ago I bought two of them for $35 or so each, brand new in the box. People go nuts when the price of gas goes up.

R.