Looking for an investment piece? Stick with either a Patek Philippe or a Rolex, which tend to rise in value most. Aaron Rich, vice-president at Sotheby's and head of its watch department, suggests the Patek Philippe ref. 130 (pictured) in yellow gold. "Other versions are selling for three times the price," he says of the roughly $40,000 watch. Too much? Rich says the Rolex Pre-Daytona ref. 6234 (about $25,000) is also undervalued. Hello, nest egg.