Thought I would add the IKEA Komplement cage here too:
IKEA Komplement Cage1 forum.jpg
Build Video:
Ikea Komplement Hamster Cage | Full DIY Tutorial - YouTube
Approx £96 to build or maybe a little bit less.
Tools you will need are a drill, saw, screw and staple gun
Cage internal measurements: 96cm (length) x 57cm (width) x 55.5cm (height) = 5,475 sq cms = 848 sq inches.
Cage external measurements: 100cm (Length) x 61cm (width) x 57.25 (height)