Had to research this for a roommate: found some interesting stuff out there. If you have a newer laptop, it probably has an ExpressCard slot you can use to add a PCIe device to.
* Offical list of ExpressCard addons
* "Magma" box: ~$700; need your own card
* ExpressCard to PCIe x16 adapter ~$80 : add power supply, video card, and probably an enclosure too.
I saw a blog post a while back regarding the last option, so I know its doable.