@Argon I recruited a 3d artist and a 2d artist (5 years ago) from other forums (3dsmax forums) and we had some accelerated dev time by modifying bought assets. They of course could also create fitting original content. The licences allowed us to both use the assets in game and modify them. The limit was we could not resell the assets or the modified versions. I do not know if this is the Unity licence and limits. However bought assets should not ever be a stop to selling a game. There is no point in owning assets that you can not use in a production game.

I suggest you do as I did and recruit artist from places they visit. Expand beyond the Engine forums and do not be afraid to look into students that are happy for portfolio work.