Depends on what you're looking for and how much you want to spend. Big brew pots with thermometers, valves, sight glass, etc can be very pricy. If you want to spend for one of those check out homebrewfinds.com. They list daily deals from all over the internet.
If you just want a plain old big pot (the route I went), Amazon has great deals. You can get a 10 gallon aluminum pot for around $40-50.
Same for the burner, you can spend anywhere from $40 to well over $100. I went with a turkey frier setup from Home Depot. I found a crazy cheap deal for like $30. Included the burner and a 30qt pot. I have since moved up to a 40qt pot, but still use the 30qt as a dunk/sparge pot. I BIAB. The burner works fine for me. Gets 5gal of strike water to temp in 10min or so. I can then bring 6.5-7gal of wort around 150F up to a boil in 15min or so.
So, it all depends on what you want. If going the cheaper route, I'd try amazon. And homebrewfinds.com is a great way to check ALL the brewing sites for the best deals day to day.
EDIT: I'll add I just bought a bunch of stuff (new perlick taps, beer line, posts for a keg, etc) from Adventures in home brewing and they had solid prices.... at least for what I needed.