Consider what type of down or feathers are best for your project.
If you want to add some fluff to your existing bedding buying bulk goose down or duck down is your best option but if you are making chair cushions you might want to use larger feathers for added support and shape retention.
Buy less expensive duck feathers for projects like accent pillows where warmth is not an issue.
Go with white goose down instead of gray or duck if you are sewing with a sheer or transparent fabric.