We import food from every corner of the continent, and on the long term Barca should be able to feed us at a lesser price.
I've run calculations the other day and came to the conclusion that D'Hara will need *massive* investments in terms of warehouses if it is to become a strong trade hub that doesn't need to worry about its own starvation. Trade with the Zuma could allow to finance this in part, but we don't have any traders available off the bat to do this, and re-assigning one would take time. We also don't have any estimates as far as population growth right now, and since the last time we sold them food we had our worst starvation in ages, there's some reluctance to get rid of these stocks.
The prices we were paying for Aurvandil and Madina are considerably greater than what we pay anywhere else, and the massive deficits it causes prevents the accumulation of capital necessary to invest in warehouses. As such, to rely on food imports of that price is simply unsustainable, as demand will only continue to increase. Considering that to get to the Zuma Madinian traders would need to pass by D'Hara, nobody really believes Madina has any other significant trading parters to export all of their goods to, and therefore conclude that they should get the same price everyone else does.
As for relations, it's not so much of a fear of a colonization attempt of Paisly anymore as how hard it is to become friendly with someone who bleeds you dry and talks as if you would be nothing without them.
And indeed, as egamma said, Paisly's finances are pitiful. If I were greedy, I'd ask for my old title as Marquis of Paisland.
