Loving and buying watches is a disease. All the watches lovers here are affected. There is no known cure at the moment.
When you see a loved one (I mean watches), you go to any length to acquire - even to the extent to 'pawn' your other loved ones, just to get your latest holy grail. Thus in this scenario, investment is out of the picture. You be lucky if you sell at a profit, if not then some losses.
The only expenses, I see in this scenario are the expenses that ones spend on the servicing and upkeep. Definitely you would surely maintain your watches to keep them in tip top condition. Base on my many experiences, a simple service on branded watches takes you back by several bucks.
If you have deep pocket, you will surely buy a very popular model for the sake of owning it - maybe for a while. But then your investment would be tied up for as long as you owned the fine piece. Selling it later to recover your monies, its very much depends on the market forces. In this manner, I would rather (be better) to invest in shares.
As is, I have to say again, buying a watch is never an investment but an expenses all the time.
my 2 cts worth.
DC