Frank Mihal video blogs about the pricing of homes that were previously used as a grow-op. Even if they have been completely redone & renovated and brought back up to code as far as electrical etc, there still should be a 5-10% discount in price compared to others without the "ex grow-op" tag on it.
If you have any questions or comments about pricing of ex grow-ops, feel free to contact Frank at http://www.frankmihal.ca