A.S.
My daughter is 14 months, she has a fisher price booster. Here's a link: http://www.fisher-price.com/fp.aspx?st=2001&e=detail&....
We found ours at Babies R Us, Toys R Us also has it.
We LOVE, LOVE, LOVE this seat! By far the best baby purchase we've made (and it was only $25!!!). We use it at home, take it to restaurants and other people's houses. You can use it with the tray as a highchair or without the tray. The seat has straps on the sides and bottom that secure it to the chair, then there are also straps that go around your child's waste & between their legs. The white tray is removable and dishwasher safe. It also has a lid to go over the trays to keep them clean for travel. I can't say enough about this seat, I rave about it to everyone. Every time we go out with it someone asks about it. It's fantastic! :)
If you use it without the tray and just have him at the table, I'd invest in some of those bowls/plates with suction cups on the bottom, or be prepared to have dishes picked up, thrown or dropped. It might take some time for him to get used to it, but I don't think it's too early. Sometimes we go without the tray, we just have to keep a close eye on her.