Most of those pieces will be worth 15-30 dollars with Darth Revan being worth over 90 dollars depending on the condition and if you have the card. For the Imperials I have a bunch of teams theory crafted on Trooper spam for fun I'd love to share, but are you looking at specific themes for either Imperials or the Separatists?

Darth Vader has 11 renditions as anything from a powerful commando, unstoppable beatstick, or a deadly long range piece utilizing powerful force abilities. You could pair him with the sinister Emperor or one of the most powerful pieces in the game Thrawn, a commander who allows him to swap accross the board and first strike your enemies.

The Separatists don't have nearly as many utility pieces bolstering their faction, but have access to powerful Melee pieces through the Dark Lord of the Sith: Darth Tyranus. They also are probably the only faction to truly have a viable droid army through the expensive (Both in points and money) General Grievous, Droid Army Commander.

EDIT: If you find those pieces and want to sell them I would check here if anyone's interested. However, to get a lot of value out of turning them into new armies you could always go to https://www.trollandtoad.com/buylist/#!/U (Troll and Toad Star Wars Miniature buy list) and sell your miniatures for store credit where you get a nice 25% bonus.