It is unto what kind of position you have, the higher, the bette

1, only moving, air fare for whole family once,

2, house-hungting trip, some cash up front. 

3, sell your old house, buy new one, pay closing costs. 

4, 4 times air fare for the whole family, very rare.

5, low morteage rate, sometimes, even 0%

It is all upto how hard they want you join them.