Leigh Griffiths, Vaclav Kadlec, Vincent Enyeama. Obvious ones.
José Castro, Nashat Akram, Chuklei, Anderson - Free
Eneramo, Gino Clara, Castro, Dennis Appiah, Nicolás Cambiasso, Juan Quero - Not free, some cheaper than others
Rinaldo - Free in January
Schelotto - Free end of first season
Sime Vrsaljko, Ivan Tomecak - Both around 1M
Best you identify strenghts and weaknesses and ask for a specific player really, there are a ton of lists around and we can parade a crapload of names, but the more specific you get, the better the suggestions
Have they updated Gai Assulin yet? Gauthier Mahoto's available on a free.