Keys price inflation/deflation?

This is my first time really playing a season in D2R ( I normally play offline because I hate trade, but Traderie has made it bearable)

I believe that most uniques drop in price after the first week or two, but what happens to keys? I’ve been collecting 3x3 sets and I’m wondering whether I should be dumping them asap or if there is no rush…

Also, presumably high runes inflate in price as the season goes on? Correct me if I’m wrong….