I made a playpen using storage cube panels - plastic ones not wire ones. It's tall enough that no Syrian has got out of it, though it is a supervised activity only (and I make sure toys aren't near the edges). The pet shop play pens are very easy to escape, even for a Chinese hamster.
I like the plastic one because it can be cleaned easily, it folds down nicely to store, and it can be adjusted according to how big a pen you want - you can use more panels if you choose. I wrote about mine
here and
here is the original thread where I got the idea.