PP here: yes, fiberglass is common and up front is definitely the cheapest, but if you plan on living in the home for more than a couple of years, and the walls are going to be open during a renovation, I would splurge for the foam. Your energy savings will pay for it quickly and it will be a huge selling point when you do sell. In a typical 2/6 wall, you can get R19 from fiberglass, but up to R34 from foam.

Thank you for the response. Fiberglass batt is most common and cost effective I think

Depends on what kind of insulation. Fiberglass batt is probably $500-$750, closed-cell spray foam is probably closer to $3,000. I recommend watching this video for some tips:

http://www.thisoldhouse.com/toh/tv/ask-toh/video/0,,20543103,00.html

Hi, we're renovating the entire house. Just wondering what would be the estimate cost of insulation JUST the materials for a 1600 sq ft town house. Thanks