My biggest advice to newbies shopping for backpacking/camping gear is: borrow before you buy
! I find that a huge percentage of people are excited about getting their own gear or are afraid that other backpackers won't want to share, so they invest a lot of time and money into stuff that they later discover doesn't really fit their body/activity/hiking style. However, if you borrow someone else's gear for your first few trips, you can get an idea of what fits or doesn't fit before
you buy anything. Slightly less romantic, but it saves you a lot of headache in the end. And I know very few seasoned backpackers who don't have extra stuff and aren't willing to let someone else borrow it for a weekend. (I speak this from personal experience, having gone through 2 whole generations of gear before I got dialed in to what I want!)
That being said, gently used equipment is usually a good deal (typically the result of someone who did just what I described above!). In addition to Craigslist, you can try ebay, geartrade.com and practicalbackpacker.com's "for sale" board.
For new stuff, I almost never pay full price for any brand name stuff. There are SO many discount sites out there - steepandcheap.com has daily deals (but watch their % off, sometimes it's exaggerated), backcountryoutlet.com, sierratradingpost.com and campsaver.com all have pretty good deals sometimes. My favorite when I was getting started was campmor.com - they tend to carry lines of less expensive gear, and I've rarely seen their prices beaten.
As for brands, Kelty and Jansport can be good for inexpensive gear, but their stuff is often unnecessarily heavy and doesn't last in my experience. Better to find a better brand on sale, like Golite, Marmot, Osprey or Big Agnes. And always figure that the lighter something is, the more comfortable you will be on the trail (for the most part) - I balked at that idea for years, but now I am a firm devotee. Finally - on shoes, I'm telling folks now to be careful with Merrells. They just haven't been lasting for me like they used to.
There is way too much info out there - you can totally overwhelm yourself. Just keep in mind that it's all about having a good time outside, and no matter what you buy, it's your attitude that counts most!