Lowes used to carry "Peel&seal" I have seen people use this before a whole lot cheaper than you "sound deadener companies" the lowes peal and seal is asphalt based wile most of your deadner compaines are butyl based...Some of the deadener is asphalt based as well..But depending on your climate conditions I would think twice In doing your "home improvent" deadening..As if you live in a warmer climate you will be dealing with a mess,and will be pissing in the wind to keep it applied to your trunk lid.ect.. If you have the budget I would suggest a reputable deadener company and butyl based material.Peel & Seal is pointless in a car. Complete waste of money.
He also asked for mass loaded vinyl NOT deadener. Two completely different things. To block sound you NEED MASS. No other way around it. You also "cannot" have any leaks so 100% coverage is the goal. You might also read I said I would not suggest this,being you took time to read the post You implied it was worthwhile for something, that it isn't. I clarified.
Plus he has deadener NOT at all what he asked for. He asked for MLV which you could generically just term as ANY heavy sheet material. Deadener is really light and sucks at blocking sound.