We have the same panels, and yes they do hold up good! We can safely keep a horse in there when needed and we used it for training. : ) Not sure of the price you said, sounds a little high, we had to shop around and i am sure there was as much as $20 difference per panel in prices, but I just cannot for the life of me remember the final price!
Oh and congrats on your vet clearing the horses! : )
I thought I would start with a round pen and gradually turn it into an arena. I asked for an indoor one for Christmas but all I got was a "are you crazy?" look. We are going to have a barn raiser in Oct. All yall are welcome to bring your hammers and come down. All the BBQ you can eat!!!! (grin)