Best answer: For the standard, general-purpose resins for your Elegoo Mars, Amazon is the cheapest and easiest place to go. If you're looking for more specific resins, castable resins for example, then Matterhackers is much more likely to stock what you need.Keep it on Brand: Elegoo Mars 3D printing Resin (From $25 at Amazon)Specialty resins: MakerJuice WaxCast Resin ($120 at Matterhackers)