Have you checked out the Act! website yet? They seem to have a Cloud service already. And based on the screenshot, it's hosted in AWS. How many users is a factor worth considering, and afterwards running some numbers at the cost calculator.
Right off the bat, the fact you're calling it "database" shows you don't want to be in Excel.... there'd be no control... Person A could change a lead from Person B, and it'd be difficult to track down.. and even more difficult to prove. This isn't even touching on the corruption potential of multiple fingers in the same file..
I don't know if it's sold in your country, but I think ACT! does what you're looking for. Might be worth investigating.