Can't beat proper insulation! After seeing some newer techniques the last couple of years(around here) first hand, If you can't afford spray foam everywhere, my next option would be dense pack cellulose. I haven't seen the fiberglass done this way however, but was under the impression that fibeglass was not supposed to be packed to be efficient. Things change, I'm sure. Getting back to the cellulose, I have first hand seen this in homes and pole barns with remarkable success, it even helps control outside noises from penetrating. In one instance, a contractor built a new home near a railroad track and the results for the noise reduction are outstanding. IMO. All insulation if properly installed will definately help. I am wondering just what you are getting for spray foam R factor. The total price seems low. Closed cell spray foam is going for $1.00/sq. ft. per inch around me from 4-5 differant reputable installers. Just check that out before proceeding to make sure you are going to get the R factor you want.