You can ask the trader to find any item you are missing. His services are available to you starting from level 14.
Without discounts you can hire a trader for 12 Megabucks for 1 day, 50 for 5 days and 90 for 10 days. In addition, you can hire a trader for 1 time by spending a special coupon.
After the trader has brought goods, he must rest for 1 hour. The rest time can be reduced by 2 times with the "Fast Trader" scheme. The scheme is valid for 1 day.