Rabbit grazing area?

Ok so normally I just let my rabbits out into the yard and let them graze while I am keeping an eye on them, but after my scare yesterday with the rabbit running away I figured out that I needed a better system! I used to put adult rabbits in a child's play pen but it has been broken beyond repair for a few years now! I don't want an grazing ark I just want some kind of kid's playpen with no bottom and no top! Any ideas?

We have a 30" tall collapsible wire pen we got from Petsmart. might need to get some garden wire to put on the ground so they can dig their way out.

I've got a couple of these and love them...they fold up and are pretty easy to move from inside to outside.

http://www.petco.com/product/13904/Midwest-Black-E-Coat-Exercise-Pens.aspx