In all honesty both can cost a pretty penny. I primarily work with foam so, I can't say much for cardstock & fiberglass. It's to do your homework and research to get the best prices for your materials and tools.
With the foam, contact cement, super glue, knife, replacement blades, ruler, cutting mat, cardstock, sand paper, heat gun and rotary tool, costs were already over $150 Canadian. On top of that I purchased both Modpodge and Plastidip for sealing and then there is paints.
Don't let my list scare you. All this stuff doesn't need to be bought all at once. Especially if your budget is tight. Buy things as you need them. Paints for example. Save those for last since you would still be in the build stage.
Hope this helps a bit.