The buyers will starve, the sellers just make a bit less gold. I think we all know who has the bargaining power here.
Not really, because the buyers have friends and plenty of realms to chose to buy from.
For example, while D'Hara may not be self-sufficient in terms of food, the 'moot is as a whole. We trade with other realms because that's what we do more than out of need. But if they want to jack the prices of their food, then too bad for them, we'll just pass and buy elsewhere.