Some years I like to save my strategy items to put them in sets to upgrade to the rare or epics higher quicksell value.
However, this year the quicksell values do not increase any more than the total value of items you put into the sets. Might have been that way last year as well. I just don't remember.
Also, I don't believe the epic strategy set is available yet.
All that being said, is you've been playing all year, you've probably got about 600K+ coins worth of quicksell.
This is great time of the year to clean out your binder. And the strategy items are a great place to start