Very cheap egpu adapter can use either expresscard or mPCIE.
List of components needed
3mm thick cardboard (check a retail store for empty boxes)
Graphics Card - Nvidia GTX 750Ti or any other as long as is PCI-E (Amazon, eBay, any other store)
EXP GDC Beast V8 - PCI x16 Connector (Gear Best)
Xbox PSU 150/175/203W, Dell Y2515 DA-2 220W or a PC PSU, depending on your GPU Power requirements (Amazon, eBay, any other store)
Xbox to Xbox Slim PSU converter Cable (eBay)
USB Male to Female Cable is optional (eBay)
HDMI Male to Female Cable (eBay)
Adhesive sticky Vinyl, color of your choice (eBay)
DEMCiflex Dust Filter (Amazon)
Tools used: Hobby knife set, cutting mat, Stanley knife, ruler, measuring tape, superglue, welding iron and... ALOT of patience.