They won't talk about any bags over the phone, they'll get in trouble doing it as it's against store policy to discuss pricing over the phone.
That is true, but when I rang about a bag that was in stock - the SA told me the price for the bag over the phone.
This year I have visited a number of Hermes shops and many in my travels over the years - all seem very helpful, but in the US I find the one on Rodeo Drive most helpful and the only one that actualy said that they get a FEW birkins EACH week... (I think perhaps that is why Victoria B has one in every colour).
Also, remember, SA's are ordinary people and its always worth while getting to know one. They love it when they get asked by name! and the true secret of going up the list is simply knowing to say the right things... and they can bump you down and off the list too being human.
Good luck...