I filtered Walmart.com by in store availability near my zipcode. What a new parent would find on the shelves if they walked into a local store earlier today and probably what they would find on the shelves at 2am tomorrow after deciding a baby monitor solves their problems. The fact that $100 is a normal price for a baby monitor even at Walmart suggests market inefficiencies. The plausibility of the arbitrage described in your comment is premised on market inefficiencies.

Please keep in mind that I described a feasible answer to "what problem does it solve?" That doesn't mean the OP's business is viable or likely to experience hockey stick growth. It's just that after a little reflection, I realized the basis for my initial dismissal was mostly "a $100 baby monitor isn't a big deal for most people I know well." They tend to have bank accounts and Visa cards and internet access.

They tend to be better off than many people I see in Walmart.