Does the bird the feathers come from make much difference though?
yup, they may all be from the bird's preen gland but different birds have different fibre qualities, some excrete more oil than others, etc.
best seems to be from wild ducks but a lot of distributors are selling crap from farmed ducks and other fowl. specially the more-known bigger brands.
another issue is the dying process when choosing unnatural colours which necessitates removing the feather's natural oils. some processes are 'better for the feather' than others, if you will, but either way, some sort of oil needs to be put back on the feathers before being sold. standard procedure is putting farmed-duck oil but that oil isn't very good...
it's all a pain in the a-- really
outside of gathering them from hunters, these from Lucian at Troutline.ro are as flawless as it gets for wings and general fiber-only use
http://www.troutline.ro/ultra-selected-campbell-cdc-feathers-in-natural-colors.htmlanother great option is to give Steve @ Cookshill a call and tell him exactly what kind of flies you intend to tie and he'll sort you out good.
http://www.cookshill-flytying.co.uk/cdc.htmcheers,
marc