Does anyone have experience with using third party services for Amazon FBA?

Hi,

I doing research on potentially starting an Amazon store and I wanted to know if anyone has used a third party service or consultant?

These third party services state that they will setup your store, do the product research (the store will be selling many products), manage your store, provide customer support, have their own warehouse, and basically make it passive for the store owner.

They have have a startup cost for using their services along with a profit split.

It would be great if anyone knows if services are legitimate or not.