Re: questions from a new guy in california...
Welcome to the forum.....most buy the least expensive kit they can. They tend to be pretty much all the same and you get a good one or a bad one depending on you fate. All can be made run-able with little problem.
I would look to one who offers good after the sale service, or one that has a storefront in your area.
As for the ready built bike- You can get them for 200 dollars (ebay, used) or pay out the wazoo for someone else to do your work. I prefer the build it yourself route, unless you can find a complete bike on Craigslist or ebay really cheap. Just watch out for the Flakes of Craigslist who can be shady at best.