I wouldn't suggest on buying Midwest cages, they are way too small for my liking. You can buy C&C grids for $15-30 on Amazon you can get around 24 grids and it will be enough for around a 6x4 ft cage.

Here are the links:

https://www.amazon.com/dp/B078BC54SJ/ref=cm_sw_r_apan_glt_fabc_4NK5C79WP3NRAJEKHK7V