Drive from where? Rental cars from SEA seem to be in the $1150 range for pickup on 8/19, return 8/22
There's a bus from Eugene to Bend (just 15 miles south of RDM), but it appears to be sold out on 8/19 (surprise!).
Amtrak still sells tickets for $51 from Eugene to RDM (train to Chemult, 2 1/2 hr bus ride to RDM).
I wonder if there are car pool options from Eugene to central Oregon. Might be worth checking Craigslist before paying a cab $300. Scenic drive, though