Hm. Immigration happens according to wealth. It's far too easy to get wealth, or at least, far too easy to get the kind of wealth immigrant dwarves are looking for.
So I suggest a couple things. First of all, add some inflation... that is, decrease the perceived value of goods as dwarves see it (no need to do this on the fly at the moment). Second of all, make -different dwarves value different items differently-.
Peasants should look at everything. They want a better life, and if you have goods, you can probably provide a better life. They would act just as they do now.
Dwarves that create goods... craftsdwarves, masons, carpenters, smiths, etc, should value the type of item they create, as well as any tools they use (so smiths would value anvils). Having a lot, and a valuable lot, of goods of their type likely means more work for them, and even if not, there's likely some skilled members of that profession that either have or would like to start a guild, and maybe you could get some instruction from them.
Military dwarves should be looking at money, weapons, and armor. They should want to get paid, and they should want to be well equipped. Having champions should also impress them...
..In fact, I would say that having legendary of any profession should count MORE than wealth.
And so on and so forth. My point being, dwarves aren't coming to you with demands, unless they're noble, they're coming to you with -hopes-.