It was a little more than what I wanted to pay, but this radio is awesome and would plug right in with no modification as it has the same 15-pin connector as our stock radios http://cgi.ebay.com/ebaymotors/Toyota-4 ... ioQ5fVideo
Note the Aux input that will work as an mp3 adapter. I really wanted this but wanted to save money so I went with a stock single-DIN out of a 6th gen that also plugged right in and works great!
That tocoma radio looks promising. I am sort of interested in the scion one though just because of the charging capabilities of the ipod hook up, but this might be good enough for me and I can just run a power adapter.