Last year I shared in a blog post that I planned to make a bolster to match the headboard I made for our guestroom. The most promising result to my search for the right size foam insert was on-line and $30 before shipping.
That may not sound like much to you but, I am convinced that there is almost always a less expensive way to do just about everything.

After a few failed attempts with fiberfill that resulted in a pillow that resembled a giant anaconda that had just eaten a donkey, I found this solution...
...a pool noodle from the $ store, wrapped in a foam "egg-crate" mattress pad, held together with a little foam glue, and covered with quilt batting (the last 3 items were purchased from garage sales).

I'm pretty happy with my custom bolster and even happier that I only spent $3!