This document primarily links to product descriptions at (Dick) Blick, Scale Hobbyist, and MicroMark. These online retailers offer affordable pricing and a good range of products that are usually in stock.
Sure, we're talking about painting, but many paints are much the same. Brushes are critical.
You may think that you need a teeny tiny brush to paint miniatures, but realize that the point of one sharp brush is the same size as another, no matter how large the brush. Until brush size gets significantly larger, smaller brushes simply hold less paint. We use smaller brushes when we want to load them with less paint to minimize accidents. As you become more experienced, you'll become more comfortable with using larger brushes for smaller work.