I had the very same thing -every time I braked the horn would go off and I'd have to beat the steering wheel until it stopped. Very embarrasing!
I used black silicone sealant to rebuild the four rubber bushing thingy's about a year ago and it's worked a treat! Saved me about $100

I've even heard of some dealers recommending that the whole steering wheel get replaced!
Hope you know your radio code as I'd definitely disconnect the battery and wait a while before having at it! My dealer almost convinced me to let him do the job with his talk about airbag explosives and such like! Aside from that, I think you'll end up with a check airbag light if the battery is connected.