The best budget stuff out there at the moment is Silent Coat...its cheap but is just as good as dynamat etc! We use it in all of our vehicles that we build now and like I said, I cannot tell the difference between SC and other products like Dynamat!

Quick price guide that I seen online

8.5sqft £19.99
43sqft £79.99
21sqft £44.99

You wont get better for the money