Or two 80 x 50 bins(110 quart,somewhere around the 100ish range,not entirely certain at the moment!)and a 60 x 40(60ish quart,Walmart exclusive)bin to make a square meter cage.You'll spend a bit more than the Christmas tree bin,but it is still an excellent value and would be more versatile in terms of being able to position the bins in a way that fits best for the room rather than having one very long but unfortunately quite narrow bin.It would only be around $24 for the two big bins but you could find cheaper alternatives if you wanted to.The small one is $7 I think,so you'd still be spending less than $40 without factoring in materials.I personally don't consider the full cost of certain materials to be part of the bin cage since you're not going to use the full roll of mesh for the bins and will have a lot left over,same with tools which aren't going to be expensive either
Shelving is going to be more expensive and have far less use compared to the minimal amount you'd pay for mesh.Keeping it a budget cage instead of adding unnecessary expenses is very good,plus just using a shelf wouldn't be as secure internally or externally
Two of the big bins would be roughly 1,280 square inches by the way,so still a superior value with just the two bins.Of course,the additional smaller bin just boosts it to being an even better size!