You can order a copy from http://www.game.co.uk/en/games/pc-games/
The boxed English version of the game is only being released in the UK. Which is common these days for most new releases. It will be available on or around October 12th.
One caveat: time of delivery is much slower and shipping costs are higher from the UK.
Dave is/was the last "reputable" and reliable vendors left in the US for UK imports (as far as I know and I have a huge collection and grab games in the box any way I can) There were a few in years past but they have all closed up shop. Dave was the last US and import games vendor standing.
Edit: I meant to say you can get both games at Game. Sherlock now, Secret Files 3 when the boxed version is released October 12th.