Sims are great for what they are. That's sitting at your desk, playing a computer game perhaps in a purposeful way. They can help build reflexes and help with orientation, but really that's about it. They can't teach you the intangibles that come along with each flight. They can't model your imperfect model, and all models are imperfect.

Want to skip buying a trainer? Read a lot about the principles of flight. Have an idea of how things work before you show up. Find an instructor who will teach you on his trainer. After that, you might decide that having a predictable model that will forgive you for your mistakes might not be such a bad thing. Skill is built through knowledge and experience. Stick time is probably cheaper for a new guy with a trainer than with a second plane before he's ready.