Well we really wouldn't need replacements for Dier and Wanyama in midfield. Our depth would be ideal since they are all interchangeable. We would be getting rid of our more one dimensional players for significantly more versatile ones in the midfield.
Ceballos / Winks
Ndombele / Sissoko
Lo Celso / Alli
Plus Skipp if he is needed.
As for the price of our players I rather underestimate prices than overestimate. The numbers would be in worse case scenario and to show that even then we wouldn't be that much of a net spend.
None of those do what Wanyama and Dier do they are proper DM`s so they should remain as options. We need flexibility in the squad to give us a variety of ways of playing...