Why is it disturbing to you? This is for me a hobby, a nice hobby indeed, and it has little to do with investment value or monetary gain/loss from it because I open the wallet for love. It is the "cost" to enjoy life, which just happened to be partially recoverable as a bonus when disposed unlike many other hobbies. A few more points are:
(1) It is happening not only to ALS but across the board. Any asset/property price tend to go up and down. It is called "cycle" and most of the time, the market adjusts itself - so the price today may be (what is percieved to be) the right one and can remain for a very long time.
(2) If the secondary price is dropping, so should the primary market - you should get better deal from AD or gray market dealer to absorb (some of) the "theoretical loss" which may or may not actually materialize in the future in case you decide to sell it. It is really a good time to be a buyer.
Like Stephen well put, among all the watch brands which are "suffering" price down in the secondary market, ALS is one of a few, very few, reliable and well worth one that will pass the test of the time. Stop worrying and just enjoy!
Ken