I have a 6x4 folding run that I got from eBay a few years ago, you can still get the same style run but I think they only sell them in the 5x4 size now, would that be okay? Here's a link anyway!
I think I've had mine for 3 years now, maybe longer and it's held up really well. No issues with it apart from a bit of rust and me accidentally breaking the metal fasteners on the sides :lol: I only painted it last year I think too so it's been outside in all weathers!
http://www.ebay.co.uk/itm/FULLY-FOL...ES-PEN-/281367139365?var=&hash=item4182c9d425