I'd first reassure you guys that moldmaking can be fairly cheap when it comes to getting silicone and resin, but like all hobbies, it can get more pricey as you collect more tools and equipment. Vacuum chambers, different types of resin, pigments, etc. Additionally, moldmaking is a skill that can synergize pretty well with plenty of other skills. Making replacement parts, making copies of things you like to modify or kitbash, 3D printing in one material, and then making a mold for it so can you cast it in a different non-printable material. I've even seen some people who use 3D printing as a tool for improving their moldmaking by printing moldboxes and such, for complex pieces that would be maddening to do by hand.
Second is that this stuff can be iterative, especially when it comes to articulated figures and handmade toys. You can start with your sculpt, using sculpey or monster clay or whatever, mold and cast that, then refine and improve that piece, break it apart so you can add your joints and such, and then make separate molds from there, and work your way up. As an added bonus, resin and silicone do have certain recyclable properties. Resin typically bonds to resin and silicone typically bonds to silicone. So, you can break down any failed molds or castings and use them as filled to not let materials go to waste (I've got a box of old and shitty molds that I occasionally chop into chunks to fill out newer molds)
Beyond that, everything else is learning the logic of molds. This mostly means planning out your mold so there are minimal air bubbles, manageable seamlines, and minimal difficulty getting a piece out of a mold. Depending on how much clean up you're alright with, corners can be cut on some of these issues. Like not caring about seamlines as much because you intend to put extra time into finishing the piece later anyways. If you're aiming for mass production for the sake of selling, it helps to invest the extra time into doing certain things in the best way possible to reduce the amount of work and failed castings that you have to deal with later.