My perspective is from a tyer who used to buy bags of partridge and finally broke down and bought a whole skin. There's no comparison. None. In a package of feathers, in my experience with several bags bought, the vast majority of it is unusable junk. Are there some good feathers, sure. Not many. The skin has an enormous amount of just gorgeous and usable partridge feathers. I tie a lot of soft hackles, so getting the skin was worthwhile for me. Lots and lots of feathers in lots of sizes, so to me, if you're going to tie a lot of soft hackles I suggest buying the skin.
I completely agree. I use every feather on the skin (expect maybe the fluff.) Not only will you get hundred of soft hackles out the skin, the wings are great for quill wing flies; the tail feather make excellent tailing material. Lately, I've been using the grey feathers instead of wood duck as wings on smaller Catskill flies (and it's a lot cheaper than wood duck.) Shop around; you can still find #2 skins for less than $30. (Earlier this year, Blue Ribbon flies had some for $10, but obviously, they sold out quickly.)
Buying packets of feathers is false economy.