The reason they are expensive is that the keys are a part of the theft
prevention system.  There is a transponder built in to the key, and if
the correct key isn't in the iginition, the engine may start, but it
will stop in something like 10 seconds.

No amount of hot-wiring will make the car go.  The computer must "see"
the correct transponder key.  Nevertheless, $145 seems ridiculously
high.

The important thing is to have at least two dealer programmed keys.
Once you have two of them, you can buy blanks on E-Bay for under $15
(http://tinyurl.com/kvrh5) and program them yourself by following these
instructions.  It sounds complicated, but if you just follow the
instructions, anyone can do it.

Add Duplicate Key - Must have two programmed Sentry Keys

1. Insert one of the two valid keys into the ignition lock and turn to
the ON (RUN) position.

2. After the key has been in the ON position for at least five seconds,
but no more than 15 seconds turn the lock back to OFF.

3. Remove the key and insert the second (already valid) key and turn to
the ON position within 15 seconds. (The second key must not be the same
as the first key.)

4. A theft alarm light should illuminate after ten seconds and a single
chime sound will indicate entry into the "Customer Programming Mode".

5. Turn the key to the OFF position within 60 seconds and remove the
valid key.

6. Insert a new key and turn to the ON position.

7. After approximately ten seconds, a single chime will sound and the
theft alarm light will stop. Wait five seconds and turn to the OFF
position.