Insulate the pipes for less?

Marcus Mead_4

Just finished a 30' 1.5" main under an unheated crawl space with a 30' 1" dry return. 



The last time I needed to insulate pipes, I used Knauf Fiberglass insulation, it snaps on, 1" thick fiberglass, and there is even a peel off adhesive strip to make sure it stays.



Problem is, I can't get it locally, and the closest place is going to cost about $400 for the insulation and shipping.



I know this is probably the most ignorant question imaginable....  But it's in a crawl space, I'll never have to see it again...  Couldn't I just use R-13 wall insulation and wrap that around the pipe?   Sew it shut with some wire or clips?  Is there ANY less expensive option?