Honestly, I've found with NiMHs that batteries are batteries. As long as you're aware of the discharge rates, you shouldn't have many problems going generic or whatever. I've seen probably about 20 different brands of NiMH AAs and AAAs, and I've had just as good (if not better) results from generics as I have from decent brand names. I've got some lenmars, some energizers, some powerizers, and a number of different generics. I've gotten decent performance out of all of them.
In this respect, I think batteries are like stereo systems. A $500 stereo system will put out decent sound. A $2000 stereo system will put out good sound. A $20,000 stereo system will put out slightly better sound. Worth it? To some, sure. To most of us? No way.
Just don't get sucked into buying more expensive batteries unless you're super hardcore or something. I guess everyone has to be snobby about something
Of course...I wouldn't buy radioshack batteries either!

Check out
www.batteryspace.com for CHEAP AAAs. At $19 for 24, you can't help but get your money's worth.