I had to buy a new one this year - last year, my cats (then kittens) climbed my old one and knocked it over, and it snapped in half!
This year, I bought one at SuperTarget. It's 6' tall and kind of skinny, with hinged branches but no preattached lights, and it cost me $18. I figured that, for eighteen bucks, if the cats break this one I'll just buy another one. It's proven to be pretty sturdy, though; they've knocked it over twice already, and it's still intact.