Like I said I've only used ebay to invest in my Filson's to save money and have paid no more than $80 per pair.

Also look at the "Repair" section. Their products can be repaired by them to increase the lifespan.

To me it is worth it.
I'll be honest, if it's work pants meant to get dirty and worn I'd go with Carthart. Since I no longer do much manual labor (except around the property, where I use my old Cartharts) it's more for durable daily wear with style and the side pocket for my phone to keep front pockets clear. So I use both Filson's (style & daily wear) and Carthart's (dirty work).

To each their own.
Good hunting!