How To Make A Real Ice Pack for $.30

I've been reading Timothy Ferriss' book The 4-Hour Body and in it he refers his readers to a link where you can learn to make a real ice pack for $.30.  The recipe can be found here and is posted by Dumb Little Man.  It's pretty freakin' cool and could save you a TON of money.  I know I just blew $15 on some ice packs not too long ago when Luke's back was spazzing out him.  Now, I'm adding rubbing alcohol and Ziploc bags to my shopping list.  I haven't tried the recipe yet, but I'm thinking it's gonna work:

1. Take a Ziploc bag and toss in 1 part water and 1 part rubbing alcohol;
2. Grab another Ziploc bag and put the first bag in (with the solution) into the second bag;
3. Put it into the freezer.  DONE. 
4. If you like the fancy blue color, Dumb Little Man suggests you add some food coloring :)