Are the inexpensive 12V Air Horn kits that you see on E-Bay (red plastic horns, compressor, relay.....) any good?

I know that they will not compare to a real train horn, but for $20 - $30, are they worth it?

 

I had one from Napa Auto 3 horn air was about $35 used to scare the s### out of people.
Its great for the person one the freeway on there cell phone holding up traffic for every one else, one little blast and they are paying attention!
I need to get anouther one

 

anyone else?

 

just buy it and try it. I want to get a horn from a freight train.