I purchased my two-keg starter kit from Adventures In Homebrewing (home brewing.org).
I upgraded to the mfl screw-on for the lines. The picnic faucets are cheap, but work, and I'll upgrade when I design my keezer.
It seems that a single regulator is fine if you're going to be running your kegs at the same pressure. I purchased an extra secondary locally as it has allowed me to force-carb at 20psi, while dispensing another keg at 12psi.
As for the kegs from AIH, they were used. One was still pressurized and had a little syrup in it. Both work and I have not had to change any o-rings, poppets, etc., although I have some in reserve. I dismantled the kegs and gave them a thorough clean, which forced me to learn keg construction (which I consider good knowledge).
When I get more kegs, I'll certainly buy them used as they're a lot less expensive than new.
Consider my knowledge as that coming from a newbie, who has around six weeks of kegging experience, but many, many years of beer-drinking experience!!!!!!!!
Charlie