This is assuming that the kits are compatible. It also requires someone to research what kits are available. Then they have to research enough about how the kits work in order to determine how they would/could be made to play with each other. Then they have to design the glue that will integrate them. Then they have to design the enclosure, even if it's just determining a suitable off-the-shelf enclosure, and how everything will mount in them. Then they have get everything. Then they have to assemble everything. Then they have to test everything.I agree, but I think someone has already designed this, at least a clap and whistle activated switch, maybe not on one board, but it shouldn't be too hard to combine, even if its two separate boards in one enclosure. The kits and directions already exist.
Hopefully you can see how this is not something that someone is going to do in an hour and a half. Even if they do it in just 20 hours at $50/hr you are already at $1000.
And this completely ignores the issue of liability. What happens if they send this thing to you and then you start using it and the next thing you know your house burns down?