Interesting but can we just right click an save instead of paying?
I get V4V but I don't think there is enough of an internet honour system to make this work 
Introducing ZapWall! Sell your digital products through zaps. Powered by nostr!
1. “Connect” to nostr
2. List your digital product - photo, art, whatever as long as you can download it, it’ll work. You’ll need to actually host it somewhere (I could implement hosting later too).
3. Set price
4. Get zapped - user gets content
Very very alpha stage, probably not super secure in terms of guarding your URLs.
DOES NOT generate new unique urls yet (would be ideal)
Use at your own risk, but do try it out if you have a chance ;) Thoughts, feedback and ideas welcome! https://zapwall.vercel.app/
Discussion
Save what?
"photo, art, whatever as long as you can download it"
Your words..
If you post a photo on the internet, putting a price tag on it doesn't stop anyone from just doing whatever they want with it. In this sense there is no such thing as ownership digital art.
1. It’s not only for photos, you can sell anything, files, music, software, whatever… you can’t right click and save any of that.
2. You can sell art and only show a preview of it, watermarked, or small sized, crappy quility, as part of another image, whatever… you can right click that shit all you want and it’ll still look like shit.
I'm assuming the file. It needs to be publicly hosted, correct?