Enough for an isolation booth?

I just moved and the new studio room is in a garage. Cars and buses pass by the front of the house and can be picked up by mic's. I'm on a VERY tight budget and can't make any major improvements. I've decided that I'll have to sacrifice on sound and build a small "dead" isolation booth for vocals and acoustic guitars rather than risk picking up outside noise. It'll be around 6.5' H x 5' W x 3.5' D. Being that I'm on a tight budget, I'd like to make it as cheap as possible and build the walls with cheap wood(maybe pine?.) Double layer walls with regular wall insulation in between, covering the outside with low grade commercial carpeting and the inside with some acoustic material such as foam. It doesn't need to be completely sound proof, just enough to block out the cars and buses that occasionally pass by. I really don't know much about sound isolation or construction so I'd really appreciate your advice. 1)Would this suffice and stop outside noise from being picked up? (would pine be good enough?) 2)Would this be the cheapest method? 3)Is a floating floor recommended as well?

1st that is claustrophobic, but if you pursue this, rockwool is not that much more expensive than Standard Pink Insul. In some cases it's cheaper. Pine is fine for the studs, but pine for the actual walls will cost you more than sheets of drywall and require a lot more work to manipulate. Can someone say Utility Knife??? For your iso booth, if it were me, I'd float it. The cost of the neoprene I cant imagine running more than 20-30 Bucks very high side for the small amount you'd need to float this portabooth. I am 6' tall and 6.5 feet is awfully Low. Are all the peeps in Brooklyn Short now???? Korea.... Now thats another story. (If I offended anyone, do a club tour in Japan or SOUTH KOREA) and at my height have to duck to get in all the rooms. This is reality. What happens if you get a girl in heels. You know how that can be. You suggest taking the heels off and they look at you.. with that look. LOL. Using the right thickness and density of materials you should get pretty good results. Till Mr 8 x 15" SUBS in the back of the Escalade drives by.