From ThinkGeek... store all your data with the best ship in the 'verse.
Let them know your boat was made by the best. From Quantum Mechanix.
A cool way to show you're a browncoat while still sporting a colorful T-shirt.
Could also look shiny dangling from your rearview mirror or whatever. Via ThinkGeek.
In case your bed just doesn't feel comfy enough without a Firefly-class spaceship among the pillows. Love the wee shuttles. From QuantumMechanix.
Possibly the most detailed Mal Reynolds figure ever, and they even pretty much got his face right. From Quantum Mechanix, but not shipping until 2015.
Figure out who helped the Alliance capture River. Spoiler alert: Jayne did it.
Available via Entertainment Earth
The Buffy figure is here, and there are also links to get Angel, Spike, Willow, a Gentleman, Oz, Goth Willow and a ton of others.
These are supposed to be available by the end of the year from Titans, so I would just keep hitting refresh on this page.
It's a bit older, but this ThinkGeek exclusive is still really, really nifty.