Wow, I paid over $300 for my mountainsmith sled, maybe 20 years ago. I used a lot of kids sleds, but I started losing gear over board when they flipped over, and they will, so I got a good one - they're now Kifaru. Just be aware that performance always comes at a price. Don't get a system that is too sloppy for your purposes.

OTOH a really light sled strapped onto the back of a pack can be pulled like a sled when the going is easy, and picked up and carried when it would take less energy than pulling it.
Jim