I got the small pet rodent playground from Tesco, on sale at Â£4. They were Â£8. They are hard to get and not all Tescos has them. Here is a link for one with the same measurements from Zooplus. We have them in the run for about 30 to 45 mins and they are right beside us. We keep the toys away from the edges and they like to stand on the top. They are like little meerkats lol. They haven't tried to escape so far. I would really recommend the run for them.
I have a similar run which I got from justforpets at Burton on Trent. I bought 2 for Â£20 and they join together to make a massive run. My gerbils can escape from it so I watch them carefully; they play happily for about 15 mins then try to escape! They can get some good speed up but I can always catch them to put them away as they are contained. I also use it for floor time for my piggies and they don't climb out!