I am finishing our basement and had the drywall professionally hung and muddeded/tapeded last week. I put R19 one layer vapor against the subfloor and a second with the vapor barrier facing down to the floor of the basement. This left what a 3-6in gap between the two. When the guys were hanging the drywall you could tell the screws/drills were quieter compared to the other parts of the basement. Not drastic but a slight noticeable difference.
I am in the same boat as doing it right would about double the budget of the entire basement. This phase of the HT was more define the space, put some decent entry/budget reviewed gear in it and in a phase 2 do some proper sound proofing. Was talking with my aunt over the holidays and where she works she does industrial sound proofing and like many of the pros on this board it was all about decoupling, weight, snot, and what have you.
If there is a movie it will be either all of us (wife, 3yr old daughter who is a sound sleeper and myself) or the two of us after the little one goes to bed and neither of us enjoy SUPER loud, would take quieter clear/crisp sound of loud any day. If the daughter when she is older is down there I kind of want to know it...not to be mean but you know what I mean.