Fixing rust holes with filler??

$140 for a brand new fender
2001-2007 Town and country fender eBay

$374 for this one that's already factory silver, probably because of the free shipping. Find one local and I bet it'd be half that
Factory silver fender, used
Yea, I have done this in the past with a Duster, and what you recommend is the best option. Only need it to last a year-quick fix