I've found a place that sell them, but they are kinda pricey. I am surprised no UK gerbil website out there has linked them. They seem to be sold mainly for degus and chins, but could certianly be used for gerbils. The cage has wooden flooring as well so that is tempting me if I plan to get jirds.
Hi ya, although they seem to be very well made from the pics, I personally would not pay out for something like that. I would buy the material myself and have a go- even if it fails a few times I think it would still be profitable to make your own. Also I would give you something to do for a couple of nights- would be faster that waiting for him to build it- it says he makes them to order. good luck with it.