I feel you're looking at it the wrong way, both short and long term, in the short term giving them a taste will incentivize them to want more, both in terms of trading from us, as well as wanting us to do well so we *can* make more. Not to mention giving our Runesmith something to work with while he spends his time with them without being constrained by their lack of having Gromril.
In long term, there's a serious morale boost Dawi get with the influx of *Wealth* of gold, gems, things of great value to be shaped and wrought. We trade a bit initially, and see how the 5 year trade agreement goes, and revisit it *in* 5 years to get more when both sides are even better on their feet.