Difference between the cheapest and the best. I use the cheapest, 3 gallon plastic grow bags at about $0.35 each. I've reused some bags 3-4 times, they're rugged enough. They have plastic 5 gallon bags for about $.045. I'm running a 5 Gallon Smart Pot side by side with a 5 gallon drywall pail. Just about done, stay tuned...
The most recent pot fashion is the rooters style pot, plastic with wavy sides with slits in them to keep the roots trimmed.