Can builders charge for parking space & open to sky balcony

No not at all. Though I am not a lawyer but, I am telling this on the basis of the following article:

https://timesofindia.indiatimes.com/city/mumbai/Cant-charge-flat-buyer-extra-for-parking-slot/articleshow/22475233.cms

There is a judgement delivered by the hon'ble Supreme court, in which it was clearly stated that " a developer can only sell a flat and has no right to sell a parking space".

It is unfortunate that courts are taking upon themselves, what are the prerogatives of the legislatures. A lower court's order can be overturned by a higher court. The judgment of the Supreme Court can be negated by a later judgement perhaps by another bench of the same Supreme Court. For instance if parking space cannot be sold, why not the legislatures make laws for that, instead of judges making laws according to their own "judgment".

If a parking lot cannot be sold, as a corollary it means that parking lot cannot be owned either. If a person has got a car, he has to be sure that when he purchases or rents out a house he gets space for his car also. The Model Bye-laws have a Tuglakian provision. It says that parking lots should be allotted to members by taking lots and allotments will be only for one year at a time. In other words if I want a house and I have got a car, first I should ask the Society to take lots and I purchase the flat only if I win the lottery. Not only that. Next year I may not win the lottery and I should then dispose of the car.

If a parking lot, whether covered or open to the sky cannot be sold, there has to be a reason for. In order to make money unscrupulous builders sell every nook and corner of the property not allowing even moving space for the residents. For instance in the compound surrounding a building parking lots cannot be sold by the builder, who is not himself going to stay there. But if there are designated parking slots in the plan, which are approved by the authorities concerned, there is no reason, why they cannot be sold. The Municipality in Mumbai has a formula to calculate the capital values of a parking  slots in order to compute property tax. Only some thing, that can be owned, can be taxed.