i got a roll for about $8USD at home depot, a roll that was 5 feet by 2 feet, plenty for most cages if you have a decent frame. it's definitely not good to make the whole cage out of it cuz it's rather pliable.
Thanks OnlyOno, I live in England. I already have a cage but the bar spacing is to wide for my girls. I was hoping to cover it in some hardware cloth to save me having to buy a new cage. It's a big cage so I'm thinking I'll need to rolls.