For oils I feel the only one necessary is olive oil. You can mix it with herbs in a bottle and set it in a warm, dry, dark place to infuse the plant materials.
Mineral oil can be used for widdershin magic, but I prefer castor oil.
If you have a wide variety of herbs in your kitchen cabinet then you aren't in any need of buying other herbs. Most foods used for cooking have every magickal correspondence you'll ever need. Key ones are basil, thyme, pepper, salt, cinnamon, clove, bay leaves, and sage.
I also use lemon juice, honey, milk, oats and vinegar (not together! Lol)
Teas are awesome to find herbs that are not used for culinary purposes. Passionflower, chamomile, lavendar, and rosehips are common herbs you can find in tea. I like to call them singles packs for spells! Just rip one open and use. =D
The only other scent I buy that you can't get from a grocery store is dragon's blood. Its my personal favorite. You'll find one of your own though I'm sure. Everyone has their own staples.