Thanks for the head up, a quick search turned up the same horn on eBay with free shipping for $32 here:
http://cgi.ebay.com/ebaymotors/LOUD-SOUND-Compact-AIR-HORN-Car-Boat-SUV-Truck-613R_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a2Q 7c39Q3a1Q7c72Q3a1171Q7c293Q3a1Q7c294Q3a50QQ_trksid Zp3286Q2ec0Q2em14QQhashZitem563378a371QQitemZ37023 0731633QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso riesQQsalenotsupported#ht_4780wt_1004
I will definitely be doing this and hopefully I can figure out the wiring. It appears to be I wire the horn to the relay and the relay into the existing horn wiring.
Also, this is unrelated, but is anyone aware of a switched power source in the front trunk?