Replying to cold emails asking for freebies in exchange for "marketing"

How do you respond to cold emails asking for free products in exchange for marketing such as "shoutouts" in person or online? My work is in the fetish community, and I recieve emails from people on a regular basis asking if I will sponsor so-an-so competition, or munch, or raffle by donating an item. The email is always the same by offering in exchange a shout-out about my brand. I always delete these emails because my products are too expensive to just be giving away and if I did that every time someone asked, I'd make no money. The freebie-for-shoutout marketing never generates traffic. I've done it at vendor markets where the booth fee is a low cost fee + a item.

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Anyway, I have a few emails in my inbox currently from people who are doing follow ups on their email. I guess deleting it and moving on doesn't work on people that are persistent. How do you respond politely or professionally to freebie cold emails?