UBAD always has new inventory coming in. It's very difficult to judge when a specific item will be back in stock.
Generally the very popular items are only out of stock for 1-2 weeks.
However, the best bet to find out when items are back in stock is to add the item to your wish list and join us on Facebook. We make announcement when the popular items come back in stock.
If you request a hard to find part or product, please open a ticket so we may help you acquire the items.