I used to open most of the decks that I got, and still do to an extent. My unopened collection of decks is much bigger than it has ever been before though. Value-wise, I have opened decks of Sultan Treasury, Tendril, S&M v4s and Split Spade Lions, all of which I've seen go for 30-40 bucks on ebay. I only paid 10, 12, 13 and 20 dollars for those decks respectively, and if I bought them at what they're going for now I might've been more hesitant to open them. The most expensive decks I own (and their value fluctuates based on auctions I've seen) are Gold Arcanes, White Monarchs, Bicycle Actuators and Brown Wynns, but I have not yet opened them.