A few years ago I attended a DwellStudio sample sale and bought a lovely duvet and sheet set for our "master bedroom" (okay, it's the only bedroom). It was severely discounted and, interestingly enough, found in the kids' section. Since then I've made it a point when shopping to check kids' stores. If you don't mind wading through some of the no-doubt-about-it juvenile designs you may hit on something with adult cross-over appeal. As an example, here are some options for organic bedding for full-sized beds or larger from kids' stores.
These are just a few examples - check back seasonally to see what may be new at these companies. Note: PBTeen and Land of Nod also often sell solid organic cotton sheets.
1. Ovals Grey Reversible Duvet and Sham Set (full/queen $184). Shown with Zig Zag Chocolate Sheet Set (full/queen, $170)
2. Filigree Blossom Reversible Duvet and Sham Set (full/queen $206). Sheet set (full/queen $170)
5. De-Vine Duvet Cover & Pillowcase (full/queen $99, pillowcases $28) and Sheet Set (full $99/queen $119)
6. Nouveau Floral Duvet Cover & Sham (full/queen $119, sham $32) in three colorways and Sheet Set (full $99/queen $109)