I have never tried this at an actual Cartier boutique, but if you buy from an authorized retailer, you can often negotiate a discount on their watches... before I bought my Omega Constellation several years ago, I had thought of getting a Tank Francaise, and I was offered 15% off right off the bat when I was shopping.
I doubt you would be able to get a discount at the boutique... I think it's like with Chanel, where you can get it on sale at saks, but not at the boutique.
This is correct. When I was shopping for my newest Cartier, an authorized retailer immediately pulled out his calculator and gave me the discounted price. I didn't even have to ask.
I went back to the Cartier Boutique and asked for the same price and he was unable to give it to me, although he offered to lower the price somewhat... just not as much.
The Boutique will not negotiate until you have the money in hand such as justpassingby had (or a CC).
The Boutique did not give me the lowest price, so I ended up going to an authorized retailer.