And many a time when I'm asked this, it's the same answer I give, because so many of the more unusual ingredients are available in one place. N Essentials www.n-essentials.com.au/shop/oils/essential-oils/page/2/
Essential oils that are free of carrier oils, additives and are actually pure (not chemically produced) are something you use often in all these DIY recipes. While I use medicinal/therapeutic grade essential oils for our first aid and healing, those therapeutic grade oils are a bit too good (and pricey) for things like soap, candles and some cleaning products. For example, I saw a soap recipe that called for 5ml of Rose essential oil. Now, therapeutic grade rose oil can cost about $350 for 5ml! There's no way you'd put that in soap. And I saw another soap recipe calling for 5ml of helichrysum essential oil. But 5ml of the therapeutic grade costs about $130! Again, you wouldn't put in soap, or anything else non-healing related!
But on the other hand, you don't want to use low-grade 'essential' oils that most likely have additives and defeat the purpose of making your own pure products. I've had essential oils from ebay that fit this category. They very obviously smelled like they had carrier oils and/or additives in them. And please never buy or use the fake essential oils from $2 shops. You can't produce real essential oils at those prices, they don't smell genuine and I don't consider them safe to use.
N-essentials essential oils are great for these DIY recipes where you want quality, but don't need it to be therapeutic grade quality. They are totally pure, no carrier oils or additives. I tried the frankincense, bergamot and sweet orange essential oils from N Essentials and was especially impressed with the frankincense. I used it in soap, homemade kitchen spray and candles and found it held it's scent beautifully. The citrus oils were also used in soap and then washing powder. They performed well also. I think they have about 70 different essential oils to choose from. And they are stored in amber glass bottles, or metal bottles for the larger quantities (1L bottles available), which is vital with essential oils, that are compromised by plastic.
I haven't tried them myself, but N Essentials are now also stocking soap colouring powders, dried flowers/plants for soap and even soap nuts! So it's a very convenient place to collect your soap making supplies in one hit.