I'd go ahead and list them at $350 for the front and $100 for the rear. You can always lower your price.
But I gotta say... I must've been selling at a bad time, which was only a month ago. I had my front seats (same condition- good foam, seat back intact, working brackets, and one of mine didn't even need recovered) listed for a couple weeks at $150 and they didnt sell. And on mine the passenger and the back seat were in GREAT shape. (photos
here) Barely even looked like they had been sat in. Even at $150, I figured guys were scared off by the shipping. I ended up parting them out and selling the brackets (in great condition) to one guy and I've hopefully sold the passenger seat upper and lower to another. But, for now the driver seat and passenger seat are still in my garage.
I am not saying they aren't worth 350-500. To a guy who needs them, they are priceless. Including myself... I bought a whole Blazer JUST to get the backseat.
And if the buyer is close enough to pick them up, that changes the whole ballgame. That is reasonable money.
I would rip the rest of that black vinyl off and see what treasure lies beneath. It would be sweet if it were driver quality highlander trim. I may even chase after that. haha.
But, in my case, I just wanted them out of the walkway in my garage. SO the money didnt matter that much.