buying an mobile scanner antenna

[cobra50]

Hi

I bought a uniden bc72xlt handheld scanner.
i want to buy a mobile scanner antenna for my car.
I am traveling from overseas and will be in new york manhattan next week.
Which and where can i find a store that has scanner mobile antennas?
Which Antenna would you recommend for me to buy; i will be mostly using VHF frequency's

Thanks in advance