Richter has access to a large, untapped market in desperate need of basically anything the village can produce. In return the kobolds have crystal, gold, silver, bronze, as well as other ores and possibly coal. They should also be able to provide a wide assortment of potion ingredients from the tunnels, and maybe even mercenary mages. That level 35 combat mage with 6300 mana was a beast. A dozen of those would be a nice addition to Richter's forces. Trading with the kobolds would also give them the means to push the ashstalkers back out of the tunnels, while strengthening relations between the kobolds and the village. Of course all of this depends on whether the egg and Richter's mark are enough to convince the kobolds to talk instead of trying to capture the murdering robber that raided one of their clans.