Is the broker from a legit company? Do you know who the property managing agent for the building is? Anyone on the board? You can call the main line at the real estate company and the management company to confirm that the unit is indeed for rent at the price stated.

If you filled out any sort of application to view the apartment, the broker might have already checked your info and decided you're qualified. You'd be surprised how wishy-washy some renters can be when it comes to committing to a nice place, because they're still looking around in case something better comes up. It could also be a scam where he has no authority to rent out the apartment.

Do some quick digging and if you do hand over money, make sure it's never cash and don't ever transfer or write a check to a random name. Good luck