Gucci Envy is indeed a wonderful green floral. There's little to do if she likes that and only that one, but you could have her try other green florals. One could be the icy queen Chanel Cristalle, even more green and poisonous than Envy; Chanel No 19 has also a fair amount of green-ness. Piguet has a couple of nice green floral perfumes, the more traditional Futur, and the strong green leather (very s&m) Bandit (recently, I also bought the Bandit body lotion, as good as the perfume). My favorite is however Paco Rabanne Metal, a fresh green floral hiding a metallic, almost mineral note.
The Chanels are easy to find at regular dept stores like Macys and the like. For the Piguets or Metal you probably need a big town.