That wasn't the point. I tend to believe that solutions should be available, and that their availability helps people learn, more so than it hinders. I suggested a paid download for two reasons: because it could potentially provide a minor barrier to prevent people from unthinkingly looking up a solution, and because it supports the presentation of detailed, worked solutions rather than just a simple answer key. The cost is one potential means (and not the only one), not an end unto itself.