I don't think one single watch fulfills every aspect of my life adequately. Plus, if I have to let one go to bring one in, I probably shouldn't be buying the piece. Now, if you choose to trade up/out that's one thing, but I wouldn't buy something where I can only afford it if I must get rid of something else. Just my personal view on collecting (no judgement on other methods!).
Cheers,
Daos