Our long term goal is to move to the US as well. From what I've read, it should be fairly easy to get your husband a green card. If you've been married less than two years, it will be a temporary one, good for two years, if you've been married greater than two years, he will get permanent residence immediately, and be available for citizenship in three years (if I am remembering correctly). Because you won't have to prove the relationship like you did to get to the UK, it should be easier. And as of right now, it's only about $355. It can take up to a year, I've read, so you do need to plan ahead for when you think you want to move.
Due to the possible changes with the citizenship here in the UK, we are actually reconsidering how long to stay. We'll have to pay nearly £900 pounds for my ILR, then a year later, £800 for citizenship. That's if things stay the same, or if the dates of change work in my favor. My husband doesn't see us ever coming back here, but he's got two children who will be coming with us, and since we've already gone through all this, I'd hate to miss my chance if something ever does change, and we have to go through the whole visa process again. You just don't know what's going to happen down the line, you know?