My first question would be what your biggest concern is - price or result. Second would be whether you're more concerned about keeping YOUR sound from getting out, or whether you're trying to keep outside noises from getting in.

Given a large budget, you should be able to throw yourselves on the mercy of the local home improvement center. What I'm afraid of is that given that you're in the fairly restrictive confines of a mobil home, you may wind up spending a fair chunk of change in completely remodling the room to soundproof it.

For a lesser budget, there are sound dampening paddings that you can get - I'd suggest asking around at either aforementioned home improvement center or the local music store.

But also keep in mind that this ALL will do really odd things to the acoustics. Nothing short of hiring a contractor with experience in building studios is likely to help that.

M