Well you can still use Nintendo Channel stats to get a lower bound on how low the sales are, though that guy might be disappointed to find out that the sales of the top selling VC games aren't very low at all. For instance Super Mario Bros 3 has been rated by almost 800,000 Nintendo Channel users in the US.
Those rating numbers are higher than I expected, I was pessimistic because everyone is so negative about Wii downloadable games.