Good for you for on the composting! As to how to best do those repetitive cuts on the hardware cloth you have a couple of options. Your current shears are the tried and true method…one square at a time. Tedious yes but think of the forearms you're developing!
There are electric power shears, air powered and even shears that you can mount to electric drills. On such example is the Skil Power Cutter
. They all come in under $100. So, the two questions you have to answer is how much hardware cloth are you cutting in a day and will the cost of a new tool (which will need to be sharpened like your hand shears) pay for itself?
For other tool advice, we recommend the site http://www.toolselect.com
. They do a great job on power tool reviews by putting the tools in the hands of real users on the job and getting first hand feedback.