Where is there a good place to get a Bento Box? I have heard that it is something that is worth having on your bike for a race, and since its first Triathlon figured better safe to have one than not.
You can find one at most bike shops or REI.
If your race is going to be a sprint or Olympic distance, you may not need one. I typically only use a bento box on long rides when I'll be out for hours and need to store lots of food.
For shorter races I'll just stick a couple of gels into my jersey pockets (if wearing a wetsuit) or into the leg gripper of my shorts so they are easily accessible on the bike.
That being said, it's convenient when I need it so I'm certainly not trying to steer you away from buying one.
The Dark Speed Works one is the best. They have different configurations based on your bike. I have two!
Another good place to shop is my gear closet. I have 2 Profile Design E-Pack Bento Box's (one red, one black). Think they are medium or large. One is brand new and still in the package, the other is black, and I've taken it out on probably... 2 rides?
It functions really well, but I don't seem to really use it, as it doesn't fit particularly well on my TT they way I have things configured (I know they work on others, I just have cables in the way), and I tend to just use my pockets and stop at stores along the way. Fits fine on my road bike and stores plenty of food and my cell phone. I see great utility for long rides where you don't want to load everything into your jersey pockets.
I'm happy to sell one or both to you if you're interested.
I have two I can sell you for about $5 ea. One is Bontrager. The other is larger and is branded with Austin Tri Cyclist.