Well market value plus some premium for inconvenience of not being able to choose sounds fair, perhaps FMV + 20% or perhaps up to 30%. These are large amounts of money so perhaps the premium should be an absolute not percentage value.

FMV +10% for tolerance of estimate of FMV + 6 months average salary in the area would be generous enough to recompense the hassles of relocating.

Remember surrounding society, that is hundreds of thousands of other people, benefit from the infrastructure being developed.