Grant Kirkhope, composer of Perfect Dark, Banjo-Kazooie and Banjo-Tooie, has posted the soundtracks for the trio of Rare games on Bandcamp, where you can name your own price to purchase each.
Kirkhope posted the albums on the service over the last month. The Perfect Dark soundtrack contains 36 tracks, while Banjo-Kazooie has 17 and Banjo-Tooie contains 14. Each is available at a price of the buyer's choosing and can be downloaded as MP3, Apple Lossless, FLAC lossless or Ogg Vorbis codecs.
You can check out each soundtrack using the links above. According to Kirkhope's Bandcamp page, he began working at Rare in 1995 and composed the music for many of its games. More recently, he was the audio director for Kingdoms of Amalur: Reckoning.