If you love Tycoon games...stay the hell away from this one. Zoo Tycoon doesn't deserve to be called what it is, you cannot lose, you cannot get behind, you are not challenged in any way shape or form. If you want to spend your time waving at crappy looking monkeys and giraffes, then by all means..spend 500+ bucks.
Or just read some reviews and watch some gameplay videos to understand what this game really is.
Ultimately my suggestion is wait for E3. After E3, weigh what they've announced against what you're interested in playing and decide from there. For all we know, there might even be a price drop announced this year (despite the fact that the Xbox One is selling just fine and isn't "failing" as the Sony Ponies would have everybody believe.)
Than again, I can't really talk. I bought the Xbox One full price with the primary intent of getting Halo 2 Anniversary, a game that hasn't even bee confirmed to exist yet. but I know it's getting games like Halo 5, Fable Legends, and troves of unknown Rare goodness, so I know I can rely on the XB1 to be there for me.