Thats ridiculous, and certainly wasnt a 'budget' tour, but a tour full of old couples.

All reputable adventure companies such as Intrepid, Gap, Imaginative Traveller, Tucan, Explore, Exodus or Geckos, etc do not require a single supplement, you end up sharing a room.

check out intrepidtravel.com, gapadventures.com and trekescapes.com