There are allied seals and centurio seals which I think you can buy certain crafting materials from but not everything like monster drops, and I think you can also purchase some with poetics too. I get that the drop rate sucks or rather the farming itself sucks since there is a chance of getting 3-5 items per mob. My suggestion would be to level your retainers to go fetch a few of the skins whilst you do other things so you're not constantly grinding for them. They don't bring back a lot even with high level gear but it's better than nothing.