If you like the idea, enjoy -20% discount code: BITCOINTALK
That is cool discount for bitcointalk members and I think price is ok for your product when compared to other similar products.
I prefer using stainless steel washers instead of metal plates, because they are cheaper and can be purchased anywhere locally.
I was following many stainless steel products for bitcointalk seed phrase backup, and I didn't find your plate being tested by Jameson Lopp, so maybe you should send him your plate for testing:
https://jlopp.github.io/metal-bitcoin-storage-reviews/If you have questions, feel free to ask here.
I see that shipping is free for orders over $100, but I was wondering are you shipping your plates from Europe, Poland or from other countries?