Glad you're thinking, but, no, it's a bad idea.
like @neonuke pointed out, there is no way (without a smartphone with a crypto app, at least) to verify that the private key you are handing me does indeed have the funds you claim it has. If you can invent a way they you've got something. But as is ... not.
Send you 1 btc, are you kidding, bitcoins are over $8000 last time I checked. kinda greedy, huh?