I have 4 net pens from them.. 2 I like, 2 I don't.
I bought net pen lids for all and 2 have zippers, 2 don't. The zipper is nice for quick add-remove, Plan on strapping noodles to the center of lid if using one.
If equipped with lids and a good frame it runs around 300$ for a 4x4x6.