I have had trouble finding a store that carries coffee beans. A number of the grocery stores have a large selection of coffees but they are all ground or in packets.
Maxi has some beans but mostly flavored Starbucks beans (Vanilla etc).
I did find good quality beans in Mo'orea at both Super U in Cooks Bay and Champion in Viare (near marina)
If you know of stores that carry coffee beans please let me know