$scope.getDeviceDataCost = function (device, count) {
    var i, price, lastAffordable;
    if (typeof count === 'undefined') {
        count = $scope.buyMode;
    }
    lastAffordable = 0;
    price = 0;
    if (count === 0) {
        i = 0;
        while (price <= $scope.data) {
            lastAffordable = price;
            price += device.dataCostBase * Math.pow(device.dataCostIncrement - $scope.getDeviceCostReduction(device), device.count + i);
            i += 1;
        }
        price = lastAffordable;
    } else {
        for (i = 0; i < count; i += 1) {
            price += device.dataCostBase * Math.pow(device.dataCostIncrement - $scope.getDeviceCostReduction(device), device.count + i);
        }
    }
    return Math.round(price * 100) / 100;
};