Wow, what a day!
Hey, if you *want* a highchair (we didn't for the longest time) and have an Ikea nearby, their Antelop chair is super-simple and very inexpensive. We had an Eddie Bauer wooden one (plastic tray) that was just lovely, used it for a couple months, and THE DAY he realized he could climb it, we took it apart, and within a week had sold it to a kid's resale shop.
If your girl is already doing calculated falls, I would NOT recommend a chair she'll be able to climb!
Anyway, we looked around for awhile, and one day while shopping and eating lunch at Ikea, with DS happily (happily!) sitting in the cafeteria's highchairs, we realized we could just play 15 bucks for one of those, and he's been happy as a clam (assuming it's a clam in no danger of being eaten by anyone, and therefore truly happy) in it ever since.