The most valuable deck I own is open. In fact it doesn't have a tuck at all. It's also 130 years old. If anybody thinks that modern decks are expensive to collect. Just wait until you start collecting vintage decks.
As far as the question at hand. When we talk about the value of open vs. closed decks, usually we are talking about modern decks. In general an open deck is always going to be worth considerably less than an original like new deck. . That doesn't mean that it's not worth some money though. Example- I have an sealed unbranded black Reserve Note deck from Jackson's 2nd Fed 52 project. They are still selling for well over $100 now. I was able to pick up a 2nd signed opened one for a very reasonable price. If I was to sell it. I would take no less than $75 for it, and I would get it. Not selling it though.
It all really boils down to each individual deck. If the deck did really well when it was new, and is still expensive/rare as a sealed deck. then people will pay a small premium to get a used deck, just to say they have one. In general any deck I can buy new for under $20, I'm not going to buy used. Unless I'm buying it to have as a second.