A website that does both or would different websites work? BTC to Monero works really well on ChangeNow, just don't do anything stupid to trigger the system like visiting it with TOR or send tainted coins. You can use a residential proxy for something like this. I'm not sure about cash for monero, and I feel that such a transaction would be an even higher risk than your usual cash to crypto transaction. It would be better to buy Bitcoin or another cryptocurrency for cash, and then exchange it on a website like I mentioned instead.