My personal "hope it still exists/gets preserved" grail list, aside from Bouncer:
- Vertigo - Conquest/Stern's Journey - Exidy's Snapper and Kreepy Krawlers - Surfer - Taito's Black Widow - AIM - Friday/Burble - Mrs. Dynamite - Limbo - Vampire - Fire & Forget II - Surfer - Sea Fly - Tri-Attacker - Final, non-proto version of Turbo Sub - El Fin Del Tiempo, now that it's been apparently confirmed to still exist
William's Predators, Eeekk! and Angler Dangler would have been high on that list but they HAVE been found! So it does happen occasionally!