--depends what you want to tie with it.
--you can buy a bag of feathers but by the time you strip them down to what you want to use there won't be much.
--for value and variety buy a full cape then strip it down and sort it into what you want to use for tying and trade the rest
--fly shop should have different grades of feathers so you can match with what your needs are.
--especially for drys much less waste and more and consistent material available. On the other hand no point in using a #1 cape for woolly buggers.
--talk to your local shop to see if they will give you a break on pre season order or old stock , be aware that if you try to resell they will be ticked and good luck getting another batch. That is one reason a lot of shops won't sell bulk except to legit commercial tyers.