{
    "01:30":{
        "FREE":true,
        "PRICE":3500
     },
    "03:00":{
        "FREE":true,
        "PRICE":2500
    },
    "13:30":{
        "FREE":true,
        "PRICE":2500
    }
}

public class ScheduleViewModel
{
    public ScheduleInnerViewModel TIME { get; set; }
}

public class ScheduleInnerViewModel
{
    public bool FREE { get; set; }
    public int PRICE { get; set; }
}

[
    {"TIME":{
        "FREE":true,
        "PRICE":3500
     }},
    {"TIME":{
        "FREE":true,
        "PRICE":2500
    }},
    {"TIME":{
        "FREE":true,
        "PRICE":2500
    }}
]

List<ScheduleViewModel> model = new List<ScheduleViewModel>();
//fill the model...
return this.Json(model, JsonRequestBehavior.AllowGet);