Bora Bora is quite expensive and usually hotels rates are 10-15% higher than elsewhere in French Polynesia. So I don't suggest you to get there even though I'm a FP addicted: why don't you think of staying in Moorea instead? Or to the more affordable Cook Islands? Or try a very relaxing full immersion vacation in Easter Island (departures from PPT at 600$ p.p. RT, accomodation and meals for a week?)
I also agree with FTs here saying you can find <1$ p.p. tickets to go almost everywhere...
Furthermore your spouse and you are going to travel off-peak, so an advance booking will let you spare the bulk of your budget for other expenses.
Finally, a tip concerning the place I live: if you're looking only for a sea vacation, the Mediterranean sea would not be the place to be...weather is very unpredictable and water is still too cold.