I have only used the correct pellon once. That was in the first one and it was a kig. Yes, I know it is stiffer, but after you use it awhile it all looks the same. On all the rest of them (and I have made 6 or 8) I made my own or used the cheaper stuff. To make my own I fused double sided fusible (the really cheap stuff I had on had for a billion years) to some left over batting (I generally use cotton or cotton/poly) and yes I used pieces.... Worked just as well. The only thing with these is that I found you need a really, really solid bottom, it doesn't need to fit corner to corner either. I have used 'Bagie Bottoms' (I think I spelled it wrong) which are plexi-glass rounded. The cardboard things never held up well for me.

Good luck on your adventure. These are nice after they are done, but a little of a struggle to get lining and outside together just right. Take your time and you will be successful!

Most of my totes that I want the sides pretty stiff I use fusible fleece on the exterior fabric and Decor Bond interfacing on the lining.

I used fusible Pellon for my bags, except they didn't fuse. I don't think that I will bother buying the fusible stuff again. Just use plain and quilt it. Worked for me.
Sue