The fees are something that should be negotiated between the BLFS developer and the Shopify store owner -- nobody else will be able to see them. So we probably won't ever know what developers are charging for fees.

Right, you just need a NWC string (from Alby, Rizful, CoinOs, etc.) ... and some kind of VPS with a domain name.... so far it seems like the whole thing can be vibe coded! Full docs are here: https://docs.megalithic.me/BLFS/getting-started