Check out the SWR Spectre II, they're awesome! I've got one that I use on a Ruger 10/22, M&P 15-22, M&P 22 pistol, and a Sig (name evades me) pistol. They're full auto safe and can handle 5.7 too. Along with being WELL under $400 and super quiet.
Check out silencedamerica.com ....that's where I bought mine and couldn't be happier with it.
As for the best barrel, and where to deal at home- sorry, I've got no input. I usually buy suppressors from online places and have them transfer to my local dealer on a form 3. Turns out to be cheaper than the local dealer would normally sell them.