Hi Rachel...
Using the correct brush can go a long way in the application of your makeup and results. But you don't need 20 brushes that cost over $30 each.
E.L.F cosmetics have a good selection of brushes at a reasonable price. Walmart and Cosco have beginner kits which is a great way to go.
I would suggest looking at Pinterest for makeup brush charts they will give you an idea of the basics you need.
And as you mentioned most of the makeup artists on youtube will tell you the brush they are using or they list them at the bottom in the SHOW MORE area. If you like a particular brush google the name and number and check out the price ELF is selling it for.
I believe Sephora has a video on must have brushes.
Also some women use beauty blenders for makeup application. I have found some sponges at the Dollar Store that work fine.
Daniella