Hi, I have a whole bunch of videos on playpens you may be interested in.
https://www.youtube.com/playlist?lis...nMw9Ro6wJO-zmU
Big cardboard box ones being the cheapest as it costs nothing but will need replacing as can be eaten through. The bar ones they can escape out of, although some people turn them upside down but I like to interact with my hammies so that was a no for me. I ended up using a big plastic box on wheels - which has been great for me as I can move it from room to room easily if needed. Obviously not for everyone as takes up room and some people want collapsible runs.