I would say not worth $100 but if you can get one second hand for $20-$30 they are alright.

We used ours from about 10-12 weeks and stuck the baby in it in the middle of the table while we were eating tea (big table, both there etc...). Allowed us to eat our tea because they weren't happy being shoved out of the way, they wanted to be included.

Didn't really use it much on the ground, they preferred to be held and were early sitters anyway.