FWIW, I did the trip a few years ago on a *A award on NZ that took in PPT and RAR out of BNE for 20K RT. Dunno what availability is like these days, though.

Costs can really come as a shock. I stayed in a $37 hostel near PPT (basically a private room with shared bath in a house) and $40 cottage with a lightbulb, fan & mattress on MOZ (albeit near beach). The same thing would be $5-10 in Southern Thailand. The food trucks had some of the best meals at $10-15, but there was also the baguette-and-ham bit. Other splurges includes a round-the-island daytour of Tahiti island ($50-ish) and renting a bicycle on Moorea.

Researched getting to Bora Bora by boat (deck class), but time didn't allow. Had about a week in all. Total daily outlay came to around $120, but it could feel like living like a monk. Though the place is just too darn famous not to go to at some point.