Fixed expiring duration on Mastery Books

What do you guys think about the above titled idea? Please give feedback.

First of, we all know how the prices of horntail books are inevitably dropping due to very high supply, and insufficient corresponding demands. Despite having so many new players during the present day, prices will still not go up as we have collected a huge amount of books over the years when the player base was lower, that even selling a few more will not deplete the market ever.
(and I'm talking about books like TT30, Zerk30, Blizz30, Meteo30, Snipe30, HH30 etc.)

Back few years ago, Berserk 30s and Triplethrow 30s used to sell at 300m a book, heck even Snipe30 was at least 70m a book. And now, you can find them on the FreeMarket/Horntail floor just waiting to disappear.

Of course, the longer the server exists, the number of end-game players with end-game gear who can take down Horntail faster, with less people, will only increase. Inevitably, a boss that has existed for so long will only reap less rewarding drops when the supply of its drops inevitably increase respectively.

The suggestion is to put an expiring duration once a book drops.
ie. fixed 2 week duration after it drops before it self-depletes

Why?
1. All the old pile of books that are worthless now, will disappear, leading to a reduction in existing supply that has collected dust.
2. As the market supply depletes itself (without the need of purchase & use), the level of supply versus demand can start to achieve balance.
3. When only new books exist in the market, new players will have to buy them at a higher price due to lower amount of supply.
4. To actually get another book30, players are forced to run the boss if they want to hunt for the book.

A fair example is ShadowShifter30. Just a month or two back, ShadowShifter 30s used to sell for 500k or less, and now its back up to 5-7mil. This is possibly because the number of hunted books have tanked (?maybe the crowd hunting from the mob/boss that drops the book has reduced somehow), and due to reduction in the supply, the demand from new thieves have led to the increment of its prices.

However, horntail is still an essential end-game boss and cannot be compared as easily to a mob that can be easily avoided. Therefore, the supply of books dropped by Horntail will not deplete unless purchased and used by players (ie. people will just not stop running Horntail for the forseeable future).

Given how popular books sell within a week or two now, a two-week duration upon drop doesn't sound too short in my opinion, but I am open to feedback on this. What do y'all think?