Legal aspects for a foreigner to start dropshipping in the USA

[Eostre]

I need to enquire about dropshipping in the USA as a foreigner (say, registered in another country), so that I can avoid double registration as well. 

The products that I am thinking of reselling will be from US warehouses, thus not eligible for duty.

I have read about "establishing economical nexus", however I understand that sales should be above $100k per year to be eligible.

What would your advice be for a beginner?

Thanks!