Needing advice for cheap car rentals

So I will be landing at Medford airport in Oregon, planning on making a trip up through the Oregon coast and drop off in Seattle where my gf and I will meet up with the rest of our group to go hiking. Im struggling to find the cheapest option and so far it's $1600 for 10 days

I heard from a coworker that going in person to book in advance has been cheaper for her. But if this is true, I want to know is it possible for me to go in person to my local car rental branch (Michigan) and have them reserve a car at their location in Oregon for me? Or would i have to go in person at the branch in Oregon in order to do that?