I may have something for you (if you are in Calgary of course)...
We went through this issue two years ago for my 7-yr-old. Outgrew his 16" bmx (Norco Mity Macho) but we couldn't find a 'compact' 20" bike in town for less than $500.
I ended up importing a 18" DK Intervol for him from the US. Key features that you don't find on the dept store bikes: full cro-moly frame and fork, 3-piece crankset, compact drivetrain
Here's what the bike looks like:
And here's
the manufacturers description.
I'd need to do the math, but we would sell his for less than $200 as he's outgrown it now.
EDIT:
Just realized you are looking for a girl's bike...
I've not been impressed by the Nakamura's at Sport Chek. For my 5-yr-old girl, we went with the
GT Laguna from Sport Chek instead. For not much more money than the Nak, it seems to be a much better bike (while still being a bit less than the Treks and Norco's up at the $200 level).
Plus I have a 2-yr-old girl that will be inheriting it, so I wanted to have something that would hold up for a while.