Get every unique combination in big List

Question

I have a List with about 500 items in and I want every possible combination of 10 "digits" that means I would need way too many loops 500^10

Is there a faster/better way?

Idk if code helps here since my current consists of 10 foreach and the first 10000 uniques took me 30min.

I know my code isn't very optimised but if 1 iteration takes 250ms or 25ms both in a 500^10 take way too long Thanks in advance!

foreach (var item1 in itemList)
                {
                    foreach (var item2 in itemList)
                    {
                        foreach (var item3 in itemList)
                        {
                            foreach (var item4 in itemList)
                            {
                                foreach (var item5 in itemList)
                                {
                                    foreach (var item6 in itemList)
                                    {
                                        foreach (var item7 in itemList)
                                        {
                                            foreach (var item8 in itemList)
                                            {
                                                foreach (var item9 in itemList)
                                                {
                                                    foreach (var item10 in itemList)
                                                    {
                                                        TradeUp t = new TradeUp();
                                                        t.tradeUpItems.AddRange(new List<Price>() { item1, item2, item3, item4, item5, item6, item7, item8, item9, item10 });
                                                        t.Input = t.tradeUpItems.Sum(x => Double.Parse(x.price.Replace(".", ",")));

                                                        double totalOutcomeItems = 0;
                                                        double avgFloat = 0;

                                                        List<Price> nextLvlItems = new List<Price>();

                                                        foreach (var item in t.tradeUpItems)
                                                        {
                                                            avgFloat += item.ConditionRanges[item.Condition].Upper - item.ConditionRanges[item.Condition].Lower;
                                                            var oneItemsNextItems = allItems.Where(x => qualityList[i + 2].Contains(x) && x.Collection == item.Collection);
                                                            nextLvlItems.AddRange(oneItemsNextItems.DistinctBy(x => x.WeaponName).ToList());
                                                        }

                                                        t.Outcomes.UnionWith(nextLvlItems);
                                                        totalOutcomeItems = 1.0 / nextLvlItems.Count();
                                                        avgFloat = avgFloat / t.tradeUpItems.Count();

                                                        var duplicateList = t.Outcomes.Select(x => new { Element = x, Count = nextLvlItems.Count(y => y.WeaponName == x.WeaponName) });

                                                        //t.Outcomes.ToList().ForEach(x => t.Outcome += duplicateList.FirstOrDefault(y => y.Element.WeaponName == x.WeaponName && x.market_hash_name.Contains(x.ConditionRanges.FirstOrDefault(z => z.Value.Lower < (double)((x.MaxFloat - x.MinFloat) * avgFloat + x.MinFloat) && z.Value.Upper > (double)((x.MaxFloat - x.MinFloat) * avgFloat + x.MinFloat)).Key)).Count * Double.Parse(x.price.Replace(".",",")) * count);

                                                        foreach (var x in t.Outcomes.ToList())
                                                        {

                                                            var test1 = duplicateList.FirstOrDefault(y => y.Element.WeaponName == x.WeaponName);
                                                            var test = t;
                                                            var test2 = qualityList[i + 2].FirstOrDefault(y => y.WeaponName == x.WeaponName && y.market_hash_name.Contains(GetCondition(y)));

                                                            var value = Double.Parse(test2.price.Replace(".", ","));

                                                            string GetCondition(Price p)
                                                            {
                                                                var maxmin = x.MaxFloat - x.MinFloat;
                                                                var floatVal = (double)(maxmin * avgFloat + x.MinFloat);

                                                                var itemxy = p.ConditionRanges.FirstOrDefault(z => z.Value.Lower <= floatVal && z.Value.Upper >= floatVal).Key;

                                                                return itemxy;
                                                            }

                                                            t.Outcome += test1.Count * value * totalOutcomeItems;
                                                        }
                                                        finishedTradeUps.Add(t);
                                                    }
                                                }
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
return finishedTradeUps.ToList().OrderByDescending(x => x.Profit).ToList();