I buy whatever I sort of liked and rid them when the love disolves. Mostly I tried to buy it at a decent price so that the potential break-up wouldn't cause me an arm and a leg. Problem is that:
-I paid too much attention to the resale value and often forgot what really trickles my fantasy. (Please no dirty joke!)
-I quickly realized that the selling business can easily manifest into a full time job, which doesn't quite make sense to me...
So these days I'm trying to be a lot more discerning and don't normally let myself consumate within 1-2 months of 'falling in love' so it's quite rare that I would fall out of love. Of course, there're always exceptions!
Intersting point that you have fixed a maximum. How do you come to the figure? Do you peg it to a percentage of income or networth?
The problem for setting a limit is that I realized I'm eyeing more complicated/fancier pieces as I climb up the ladder of horological knowledge so that puny limit that I set quickly became meaningless unless I revise it every other day!