i am on supplement niche but amazon ads are super competitive any recommendations?

Hello

i have an immune system support dietary supplement and i would like go with amazon ads to make some sales. I don’t have any right now.

But when i check CPC’s they are more then 2 mainly 4-6 dollars.

it is too much for me to afford so what would be your suggestions?
will external traffic work?
any help is appreciated.

Thanks