Get a second option when local repairs approach the cost of a full wall or ceiling. Compare the finished result, not only the plaster line. Add primer, paint and disruption to both options.
Reliable Dutch cost data should guide the budget, but a site check sets the scope. The cost of labor, access and follow-on decoration can be more important than filler material. Accurate cost data still needs a clear local scope.
When hiring a local plaster repair professional, compare the same plaster work and finish. Local professionals should explain why a patch, skim or removal is needed.