private void GetItemsPrice(IEnumerable<Item> items, int customerNumber)
{
    var a = items.Skip(2).Take(5);
}

{System.Linq.Enumerable.TakeIterator<int>}
    count: 0
    source: null

int[] items = { 1, 2, 3, 4, 5, 6, 7 };
var a = items.Skip(2).Take(3);

a.ToList()

Count = 3
    [0]: 3
    [1]: 4
    [2]: 5