Martinez won't leave Inter, Mateta has hit a hot streak but is no certainty to stay at this level, Schick has only managed 2 20 goal seasons and is both chronically injury prone and approaching 30 and Villa blocked Watkins from leaving for Arsenal and would probably do the same to us. I am right there with you when it comes to frustration but I don't see realistic options that are both available and can be considered any kind of certainty to score goals in the Premier League.
I would far rather we focus on top quality signings through the rest of the squad that we know will improve us and wait another season to go big for a striker when hopefully the right target is available as opposed to overpaying for a risky target and repeating the mistakes of the past. I am not crazy about Delap but I see risks with almost any target and at least as a young English forward he is someone we can use for a year or two and if he does not kick on we ought to be able to recoup the transfer fee when we move him on.