Assuming it is a decent quality name brand leather (with leather lining) on a deployant. Let's also assume:
Removed at night
Cleaned and protected regularly using quality products
Doesn't get wet - with the occasional splash when washing hands or getting caught in the rain.
Let's assume the same with:
A cheap alligator (Hirsch or Hadley ~$35)
A mid price alligator ~$100 to $150
Expensive aftermarket +$200
OE strap - Omega, Breitling, Rolex etc.
I've had good luck in the past with RIOS/Sirtoli in the mid price ranges.