insulation is relatively inexpensive. Don't use the blown in type cause it will settle. For a 2x4 stud wall use 3.5" or even 6" batts and staple it. Don't let the insulation touch the basement wall to avoid any moisture that may condense on the wall getting on the insulation, so leave an air space. Typically the back of a stud wall will average about a half inch from the wall so the 2x4 stud wall takes up about 4" of space. Why did you have to put yours out so far?