3-Pk 1kg 1.75mm Creality Hyper PETG-CF 3D Printer Filament (various) $34.20 + $4 S&H

The Hyper PETG-CF 3-Pack (pick any three colors) is currently on sale for $35.97 at the Creality store. You can get an additional 5% off with code PETGCF5 from the Creality Blog that brings the price down a bit more to $34.18. Shipping is $3.99, so the final total is $38.17. Carbon fiber reinforced PETG sits in a middle ground between standard PETG and more demanding engineering filaments. You get the toughness PETG is known for, plus added rigidity and hardness from the carbon fiber, while it still can be printed on pretty much any entry level FDM 3D printer. CF-filled filaments are generally priced higher than standard PETG, so I would use it for prints that actually need a bit more rigidity.