A Detolf would be much more suitable than a barred cage, if you can make a high lid like this to get in enough substrate:
http://i.imgur.com/5TSu6AS.jpg
http://img3.fotos-hochladen.net/uplo...locwdt3prg.jpg
Naturnahe Hamstergehege: Detolf mit Aufsatz für Goldhamster
The Detolf has inner measurements of 156 x 38,5 x 35 cm (LxWxH), which is still a bit over 0,6 m² whereas the inside of an Alexander cage is only around 97 x 48 cm. That cage also costs a lot more than a Detolf, especially as you could even get a used Detolf for less than half the price.
However, it's very difficult to fit Syrian-sized supplies into such a small width as it's even less than a 40 cm wide aquarium, so I would only recommend it if you have absolutely no other way to get something with a similar length, but a width of at least 50-60 cm. It's not impossible, though. The length of the Detolf is actually good enough and it doesn't weigh half as much as an aquarium of a similar size and the height can be fixed by a high lid, so the only thing that's really unfortunate is the width of it.