You don't need a good pen to practice calligraphy. You can buy very good pens when you are not in 50 yuan, but you'd better go to a professional store. Shopkeepers are generally familiar with this aspect and will recommend it for you according to your needs.
When choosing a brush, you should choose it according to the purpose. When writing running script, couplets, etc. You can choose a wool pen, which is soft and tender and has a wide range of uses. Purple hair and wolf hair are hard and elastic, short before wiping books and long before drawing. On the other hand, the double-stranded brush is both soft and hard, which can be used for writing and painting.
The choice of brush is mainly to pick the hair tip. The quality of a pen is mainly from the four aspects of tip, circle, alignment and key. "Tip": the sharp edge of the nib is like a cone and a circle, the nib should be trimmed neatly (it can be uneven after being squashed with water), and the nib should be full and elastic.
Take care of the pen. When you buy it, soak it in warm water (rice soup), wash it and dry it after use.