Idea 3 also sounds like the only one to me that may realistically roll in some money. Idea 1 is technically intriguing but more of an OSS side-project. Idea 2 c

Idea 3 also sounds like the only one to me that may realistically roll in some money. Idea 1 is technically intriguing but more of an OSS side-project. Idea 2 calls for legal hassles, taxes will eat into your profits and especially the "high-profile" brands that sell $10 products for $500 will probably not like you sidestepping their retail chain.