I have searched on this forum and found some threads on how much salary to spend on a watch but I think that the question was phrased wrongly as it really depends on how much disposable income a person has at the end of the month which was pointed out by others in these threads.
I say this because if someone is earning 5K a month and then needs to pay 4900 on mortgage, car etc then this person maybe only able to save 100 or 2% of their salary.
Compare this to a person earning 1000 a month but they have only 500 expenses then this person has the ability to spend a lot more (50% salary) on a watch even though their salary is significantly lower.
So my question is, how much of your monthly disposable income do you think you would save to spend on a watch you really like? If you can save 100 every month and the dearest watch you have bought is 300 then it will be 3 times your monthly disposable income.
The most I have spent to begin with is about 2.75 times my monthly disposable income.