Hey,
As the last poster suggested, renting a car out of PDX would be much cheaper if you are 25 or older.
The problem is you're trying to travel over one of the busiest travel days of the year with one month advanced purchase

. Most airfares that were any good have long since sold out.
I found a couple of options that are fairly reasonable you might want to consider:
Code:
1 - Alaska to RDM $324/person
Alaska Airlines Flight AS551 on a Boeing 737 (jet) in coach class
Departs San Diego, CA (SAN) Sun, July 3 6:40a
Arrives Portland, OR (PDX) 9:15a
Layover in Portland 45 min
Alaska Airlines Flight AS2162 on a De Havilland Dash-8 (prop plane) in coach class
(operated by Horizon Air)
Departs Portland, OR (PDX) Sun, July 3 10:00a
Arrives Redmond, OR (RDM) 10:40a
Alaska Airlines Flight AS2034 on a De Havilland Dash-8 (prop plane) in coach class
(operated by Horizon Air)
Departs Redmond, OR (RDM) Mon, July 4 5:15a
Arrives Portland, OR (PDX) 6:00a
Layover in Portland 1 hr 25 min
Alaska Airlines Flight AS256 on a Boeing 737 (jet) in coach class
Departs Portland, OR (PDX) Mon, July 4 7:25a
Arrives Los Angeles, CA (LAX) 9:44a
Layover in Los Angeles 1 hr 16 min
Alaska Airlines Flight AS4692 on a SAAB SF 340 (prop plane) in coach class
(operated by American Eagle, also American Airlines Flight AA3073)
Departs Los Angeles, CA (LAX) Mon, July 4 11:00a
Arrives San Diego, CA (SAN) 12:02p
This one has a double connection coming back, but has times that would work for you into RDM on the outbound.
Code:
Option 2 - Alaska/Eagle to PDX --June 2nd--. Then you rent a car/take a shuttle to Bend $258/person
Alaska Airlines Flight AS4730 on an Embraer ERJ-140 (jet) in coach class
(operated by American Eagle, also American Airlines Flight AA3178)
Departs San Diego, CA (SAN) Sat, July 2 1:56p
Arrives San Jose, CA (SJC) 3:17p
Layover in San Jose 2 hrs 43 min
Alaska Airlines Flight AS301 on a MD-80 (jet) in coach class
Departs San Jose, CA (SJC) Sat, July 2 6:00p
Arrives Portland, OR (PDX) 7:39p
Alaska Airlines Flight AS418 on a MD-80 (jet) in coach class
Departs Portland, OR (PDX) Mon, July 4 3:45p
Arrives San Jose, CA (SJC) 5:28p
Layover in San Jose 2 hrs 23 min
Alaska Airlines Flight AS4722 on an Embraer ERJ-140 (jet) in coach class
(operated by American Eagle, also American Airlines Flight AA3144)
Departs San Jose, CA (SJC) Mon, July 4 7:51p
Arrives San Diego, CA (SAN) 9:11p
Would either of those work for you? FWIW, the driving time from PDX-Bend is supposedly about 2.5 hours. I've never tried it myself, but a friend told me that.