There are a few commercially available bear bag systems out there for mind boggling prices. Please don't pay $80 for a bear bag system. You can pull together a simple system for a fraction of the price.
I normally bring an 8L Sea To Summit Ultra-Sil dry bag, 50ft of reflective line, a rock bag and a small carabiner. I'll add a LokSak bag if I really feel the need to hide the food odor. Typically I'm only trying to keep my food dry and out of reach of racoons and other curious critters. You should be able to pull this together for about $40 at full retail. You can easily cut the price down even further by using a simple stuff sack already in your closet and run of the mill rope. Reflective rope and a fully waterproof bag are both nice but not necessary.
The 8L bag keeps my meals organized in my pack as well. Its larger than I need for food storage but I like to throw my mug, toothbrush, towel, etc in there when I call it a night. The less inviting I make my camp site the better. Keeping the aromatic pieces of gear that invite the critters in for a closer look out of reach just makes sense.
My rock bag was lovingly sewn my my mom who is my inspiration for all of my MYOG projects. Its a nice element to have when you're out in the woods. Every time I use my bag to huck a rock over a limb I smile because I know that my mom made this for me. By the way, my rocks go over the limb perfectly the first time - EVERY time.
I keep the rope packed in the rock bag so its contained and easy to find. Having 50ft of line for bagging food is overkill but I frequently use a length of the line for this or that while out on the trail - usually to help someone else that is less prepared. I really like the line that Lawson has over on LawsonEquipment.com. Remember, support the cottage guys when you can. REI is great but nothing beats doing business with a guy that is actually out in the woods doing the same thing as you. Good stuff.