I consider the $100 bikes at Sport Chek & Wal-mart to be disposable - cheap chains, tires, bearings etc. You'll probably get two years out of them, and then they're done as a decent bike -- kids are not nearly as careful with bikes as adults are.
I would say get her the $99 bike with an eye to replacing it with a good one from a place like Bow Cycle on her 6th birthday.
