Merchant

From OGame Wiki

Merchant is a resource-trader that can be "bought" with dark-matter like the commander / officers or discovered on an expedition.

When you call him, he comes to the planet you're on at this time (if you're on your homeplanet, he comes to the homeplanet, if you're on a colony, he comes to the colony).

The trade-rate he uses is 3:2:1 (metal:crystal:deuterium). It is not a fixed rate, it can vary ± a bit. Everytime the merchant is called, the rate is selected randomly.

You can only trade as much as you have storage-capacity (example: You have 1 million metal, 100 crystal and no crystal-storage; you sell metal to buy crystal, then you can only buy max. 99.900 crystal, because then the storage is full.)

It should be noted that there are 3 different kinds of merchants. The merchant that you need to call, should be the same as the resource that you now possess, and want to trade. For example, if you have deuterium to trade, then call a deuterium merchant.

You can also get a merchant through an expedition if you find a merchant whose cargo is stuck in a gravitation field. It doesn't clearly state that you get the merchant but it says that the captain will trade with you exclusively. Then check the merchant link and you will have one waiting.