Well, the "TT" model is polyethylene, not royalex. The "TT Explorers" were significantly heavier and less expensive than the royalex Explorer. I owned a 14'TT and bought it for $599 plus tax. The 16' model ran about $200 more.
"Sight unseen," I would ask for something in the neighborhood of $600 if it's in good shape, less if lots of scrapes or significantly warped. And I've never seen a TT model WITHOUT at least some warping. I sold my Explorer 14TT for $400 or so if I'm not mistaken? And it was in good shape with only slight warping.
"Let us live so that when we come to die even the undertaker will be sorry." Mark Twain