lol Curtis is always right to the point! It's a good thing
He's hit it right on the head, once you've trained your list, you can pretty much get them to do whatever you want them to do and that's your objective, no matter what price point you're selling a product/service at. The reality is, you're always going to have a variety of people with different scales of income on your list, but it's up to you to convince all of them of why they need to buy that product/service, again no matter the price point.
I don't know of any IM'ers that conduct research from their lists (I use google for that personally), surveys yes (again as Curtis stated) and that's usually done with a giveaway of some sort.