Hamsik is the same age as Vidal. He would have given us 4-5 solid years of good football. Anything over 30 million for him is perhaps a bit excessive, but he would have been a more interesting option than Hernanes.
Firmino, Coutinho, Teixiera, Gaitan, and Fekir would have all been viable options for TQ. Perhaps Fekir would have a little bit more expensive than the others, but he has a lot of potential.