well by the rate of Cartier price increases holding on to your love is perhaps the best policy. I would probably also rather sell your unused purses in order to get the Rolex. for me both are important pieces.
Do you know if Rolex increases in price too? I thought I remembered a regular two tone datejust with diamond markers being about $8k 5 years ago... And the last I looked it is now $14k. Not totally sure though as I haven't been tracking Rolex prices, but if so then it seems to undergo pretty frightful increases as well!