UPDATE DECEMBER 26, 2015:
Thanks to Jens on the Astromech forum for extracting these. There are 73 new wav files in this download bb8soundfx-3.zip. These sounds are the new BB-8 sounds we're hearing in the film. They're quite a bit different than the original sounds we heard months ago. It appears Lucasfilm must have decided on different sound effects during editing of the film; just a guess.
UPDATE OCTOBER 20, 2015:
Thanks to Jens on the Astromech forum for extracting these. I don't know how Jens managed it, but there were a lot of good finds in the audio file. The new sounds are 001 through 019 as wav files or download bb8soundfx-2.zip.
I've cleaned up some BB-8 sound effects from youtube videos of the Anaheim Star Wars Celebration. These were done a month or two ago and should sound really good. If you're needing some BB-8 sounds for your builds you can get them here. Please note I don't own the rights to the original sounds. These sounds are not what you hear in the film, please check the update above.