Identifying authentic Yixing teapots can be tricky, just like all antiques. Yixing teapots are unique in that they are enjoyed both for art and utensils. What's interesting is that "the more and longer it is used, the better it looks". Let's call this property as "the Yixing Zisha Appeal".
Over the years, I have collected over hundreds of Yixing teapots (majority of them are fine artwork and quite many are masterpieces with a few "Peerless treasures"). Based on my experience, Yixing teapots can be divided into the following 6 categories:
None Yixing (most modern produced commodity) teapots
Old (Commodity) Yixing teapots ($100-$300)
Fine Artwork ($200-$2000)
Peerless treasures (>$100,000)
We recommend tea drinkers and collectors start with old Yixing teapots (made before 1995) for the following reasons: First, compared to modern artwork, old pieces are actually cheaper. Second, old teapots usually have very good quality Yixing Zisha clay, which would have a good appeal property. Lastly, old teapots have high historical and cultural value.
Please note we intentionally left out "Modern commodity Yixing Zisha clay teapot" because it doesn't exist. If it is made after 1995 (we called Modern era), then because of the high price of the real Yixing clay it is either None-Zisha commodity (cheap) or Zisha Fine Artwork (expensive).
Please be aware of Type 1 and Type 2, and fake TianQing clay teapots (they are all over the internet).
See Yixing Zisha Clay Teapot: Fake vs Authentic