One blue tshirt my size: $.25
1.5" elastic: $2.59
Plus one hour of sewing=Maternity Shorts: $3.84
(Which is actually more expensive than the shorts I am using for the model. If you have a JCPenney's in your area, check maternity at the end of the season. I bought maternity stuff there several times before getting pregnant at end of season sales. Most things were around $3 - 90% off.)
I used an already made pair to take my measurements from (I'm a medium)
I then took 1.5" elastic and cut 35" (I would have been more comfortable with less inches now that I'm wearing the pants. They don't fall down, but I'd like a little more snug feeling). I sewed it flat against each other, zigzagging the ends on both sides.