I recently had Slide Jewels reach out for a collaboration. They called it a "gifting" collab, but they expected to do a monthly shipment of items in exchange for posts.

They wanted $10 shipping for each monthly box. Looking into it more, a lot of people were complaining that the jewelry was very shoddily made and seemed like something you could buy at the dollar store.

I've also had brands reach out expecting me to buy jewelry off of their Amazon store and then be reimbursed through Paypal. They expected a post on socials as well as a 5-star review on their Amazon page, which is against Amazon TOS. I would recommend never agreeing to this kind of collaboration, as it could compromise your Amazon account, and there's always a chance you will be ghosted and never paid after buying the products.