I'm just starting to make a bin cage too! Definitely recommend going to B&Q as they have a huge range, i went today and got one really big box and one half the size. Only just realised when i got home that the large is way to big lol
. I'm still trying to find mesh aswell.
I've actually never been to pets@home yet as there isn't one near me. I think its a good job as i would go crazy in there.
As for costs a real big bin cost about £14 for me and the smaller was about £7, so not the cheapest you could find.