Hello Fellow,
My short answer: No, don't pay by loan.
These "buy no pay later" shops are very dangerous to fall into a debt trap.
You are basicaly paying with your future money, ...which you will of course miss in future for spending, investings, events etc.
What will you do if you need cash but have to pay rates? Well most people have to take another loan.
Loans should be taken for investments only. Means for Business or Real Estate. That's it. A watch is consumption.
There is no general nominal limit about how much to spend. Because wealth and income are individual and very different.
I would say:
Max. 1 mobthly available income. Means: Income - all expenditures (yes ALL, anual bills divided with 12) - regular investments and savings (pensiob, real estate, funds etc). What you git at the end is what you can/should afford for a consumption good.
If you are way bellow under the watch price, you can save this 1 month available income (divided by twelve and save monthly) every year till you got the needed ammount.
But this calculation is only valid if you got savings.
If not, build up savings first and be happy with sub 200 usd watches.
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