ExpressCard eGPU options and power requirements

I recently picked up a laptop with an ExpressCard 2.0 slot, which got me wondering if an eGPU solution would be feasible. I've done some research, but still have several questions.

There are two models of Expresscard eGPU adapter, the PE4L and its variants, as well as the "EXP GDC Beast". The Beast is considerably cheaper ($40 vs $95), so it there any downside to using it instead of the PE4L? I'm also puzzled by power requirements. Apparently neither adapter comes with any sort of power supply. The solution I'm most attracted to is the Dell DA-2 because its readily available and cheap, and doesn't present the safety hazard of a naked ATX PSU on my desk. But it only has one connector. Don't you need power connectors for the bridge/adapter, the 75w PCIe slot and additional connector(s) if your GPU has 6 or 8 pin connector(s)?

I've also read that using an Nvidia eGPU gives you access to Optimus, which supports some sort of compression for improved throughput as well as the ability to use your laptop's internal display. But doesn't Optimus require BIOS support? My laptop (HP Probook 6460b) doesn't have an Nvidia dGPU, so I assume the BIOS has no Optimus support.

 

Where can I buy an expresscard eGPU? All the ones I see are the ones you have to plug inside your computer

 

Check this: https://www.amazon.com/Bplus-version-interface-ExpressCard-Length/dp/B00ZI33QLY
and this: http://www.ebay.com/itm/V8-0-EXP-GD...st-Expresscard-AC773-/311865154984?rmvSB=true

EDIT: 2nd link was actually mini-PCIe. Updated with Expresscard link.