Aloha Katie,
A quick look on ebay showed a few Radio's (Headunits or HU's) in the $75 dollar area. An Aux adapter for those newer (than yours) model radio's should cost no more than $30.00 ($29.99 from Morristown Mini) but should be available in the 20-25 dollar range from 3rd party sources.
Install is easy for both and if you head over to my place, I'd be glad to do the installation for you! (Smile)
One thought, Maybe some one else knows.... Is the connector on the harness(es) Power and Audio the same from the older to newer model shift?