Firstly, at $5,200 p.a. your levies fall at the lower end of my 0.7 to 1.3 percent range – which is good, for what it’s worth.
I say that because you and the other owners will soon be collectively setting the levies to finance what it actually costs to run the building, plus anything you need to put away for a rainy day (aka, the sinking fund). Those costs include electricity for common areas, insurance, lifts, maintenance and any bells or whistles you might have like swimming pools and security or concierges. But for a small complex like yours these may not even be an issue.
To answer your question about strata levies are calculated on Unit Entitlements which is a figure that represents your share of the common property. Unit entitlements are based on complicated (to the point of mystical) estimates of value which take into account position in the building, height above ground, aspect, size and other stuff. But for all practical purposes they are (or should be) related to the value of the apartments.
So, if the developer is charging a lot more for a similar sized apartment but says the levies are the same, then there is something seriously out of kilter. There have been cases where developers have set the UIs of their penthouse aprtments lower than those of single bedroom units on the lower floors, so as to attract big spenders who want a luxury pad but don’t want to pay high levies. But these cases almost always end up at the CTTT where they not only have to put things right but can be ordered to refund the overcharged owners.
Unless the discrepancy is huge, I’d let it slide. The cost of fixing it – which means getting surveyors and lawyers involved – may well be more than it's worth.