Lacazette seems like someone I'd be in favor of taking a punt on if Benzema/Cavani can't be had, but otherwise I too would be inclined to go with what we have in the striker position. I think Wenger needs to have the balls to really commit to giving Walcott a proper chance as first choice up front though; I have a feeling he will bang them in at a very good rate if given a chance.
Also, if we DO sign a number 9 - will Walcott sign a new contract? I really don't want him to go somewhere else. It has to be a top class player to make losing Walcott worthwhile IMO.