I too went out to home depot & baught myself 10 10ft long pvc coated steel rods that are about 1.5" in diameter. They are plenty sturdy to support the weight, I cant even bend them with all my force by hand (of course i'm not standing on them either!!). They were 4.50$ each, so it adds up, but theyre pvc coated. They dont rust, and will last many a season I presume. Right now my tallest tomatoe plant is growing
almost 6ft. tall with blooms & just over gumball-sized fruit. I dont presume any problems!