The condo fees in Miami are different depending on many factors including, but not limited to, the size of the unit, amenities included, etc. Knowing the address on the property would make it easier and I'll be glad to verify maint. fees for you, but I'm going out on a limb with a couple of guesses here - the $602 seems more like a condo fee for a two bedroom unit in a decent building - maybe that price is either excellent or the unit has serious problems. It could also be that the $602 is just a mistake by the Realtor (you know that does actually happen) :) It could be that you're looking at a small, boutique building with luxury amenities, but then the price would be higher, so I doubt that. The other option is that the building has several unit owners who are in default with their maint. payments and therefore the association has decided to raise the maint. fees for all unit owners in order to make up for those who aren't paying. That is an unfortunate possibility.
Feel free to email me the address of the property of interest and I can take a look and see if it's a mistake or what the deal is. My gut feeling is that the price/maint. fee ratio is totally out of whack and there might be a mistake somewhere, but, as I explained above, there could be a true reason for the high fee.