[350]

It's easy enough to add some cheap Wolo air horns with a small compressor. I got their "Big Rig" ones, two long horns and hid them inside the bumper support, all I had to do for the power was tap off of the stock horns, so both stock ones and both air horns all go on at once. It's no hornblasters kinda deal but way louder than stock and around $30.

 

[350]

Why limit yourself to something used and factory? Wolo/Hella/PIAA make horns stock size that are dirt cheap and most are under $30. Any option like that is gonna be way louder than factory horns.