The answer to this would vary according to your duties and level of skill and how much your church can afford. For instance, are you expected to play all day Sunday and Sunday night, Friday night and travel with the choir?
Will your duties be sporadic or consistent?
Also, and maybe the most imprtant, how much do you feel in your spirit is right? Speakers do this too . . . for instance, I wouldn't expect a church that has fifteen faithful members and is just getting by to give a speaker a five hundred dollar love offering for speaking on Friday night and Sunday morning. Meals, a small love token and gas money to get home would be fine.
However, a five hundred member church should be able to give more.
So it is really difficult to answer that question.