Sold as a striker I think you'd be hard pressed to get more than Vaughan.
Sold as a winger/wide midfielder, I think with age and contract length factored in you can justify upwards of £5 million.
However crap he has been up front of late -- and he has been oh, so crap -- it has been partly down to Moyes. Persisting with him when it wasn't working and often leaving him isolated up there just made no sense. Out wide he can actually do things, and he's still only 23. He's not nearly as bad as we like to make out, I think we just get annoyed because right now we have a lot better but Moyes persists with him.