これじゃダメだわな

gistfile1.cs

public static IEnumerable<HogeCategory> CreateDummyCategories()
{
	var result = Enumerable.Range(0, 5)
		.Select(s => new HogeItemCategory
		{
			Name = string.Format("Dummy {0:00}", s),
			Items = Enumerable.Range(1, 10)
			.Select(t => new HogeItem
			{
				ID = (10 * s) + t,
				Title = string.Format("Item {0:00}", t),
				Price = t * 500,
				ImagePath = string.Empty,
				Count = t
			})
		});
	return result;
}