I have been a Naturopath for 37 years and essential oils are truthfully one of the most powerful healing modalities we use in our clinic 
For clients with anxiety we use as our first choice Young Living essential oils as the purest and most powerful oils on the planet you can buy lower cost oils that are processed with lower stage essences and broken down by additives 
smells similiar 
However the healing power is in its purity from the stage one process without additives you need three to four times the amount to get a healing response so in essence why buy cheap oils use much more whan you can use 1 to 2 drops of pure stage 1 oil and get results quickly without putting unknown synthetic carriers into your body
that is why we use Young Living oils you pay more but use less with excellent results 

see the following clips on you tube Dr Gary young clinic 1 2 &3 if you are interested in using or practising with essential oils