Was just browsing and noticed this 1080 eGPU, MSRP is $699. Some stores show stock so YMMV on local availability, but it does show a shipping option for $5.99. Online orders for shipping with Micro Center can be iffy so beware. Interestingly they still have the GTX1070 version listed at $599.99.
eGPU still is (and probably will always be) niche. I myself have the 1070 version of this box, shucked the 1070 into my mITX build and popped a Radeon RX560 in the eGPU enclosure to mess around with hackintosh which works surprisingly well.
This is probably not too great a deal for shucking the card since they've been dropping in price and you should find regular 1080 under $500 without much difficulty. And this card will look seriously ugly since it doens't even have a shroud over the fan lol.
Microcenter product link [microcenter.com]