Crate and Barrel has generally well-designed serving containers and decanters for all sorts of beverages, so I assume they'd have a stylish and functional wine port decanter.
Do a web search to find reputable online retailers and compare prices. Amazon is one of my favorite sites. You could also try to find a wine store that sells wine supplies.
Any glassware retailer should provide one. Riedl makes a nice series for decanters. Decanters should be used to separate sediment from the wine collected at the bottom of bottles.
