3D printing costs include purchasing filament, the material used to print with. Generally, both PLA and ABS filaments cost around $20/kg (USD) each. We haven’t found much difference between cheap and more expensive filaments, it’s our recommendation to go whatever is the cheapest.
You will likely get quite a bit of mileage out of a 1kg roll of filament. Below are some images showing the different weights of some of our 3D printed models.