I am trying to get an evaluation on some teapots I have , they where part of my father in laws collection that was given to us after his passing, and I would like the get a better understanding of what we have and what the interest would be in them. and how to value them, though I not even sure where to start, took me a year to work out Yixing isn't teapots, its a place

I am trying to find someone in Melbourne, Australia that could help me, but I am having no luck finding anyone that has any understanding of Yixing let alone how to value them. I understand that the prices can vary wildly, something that looks plain can can be expensive and something looks elaborate can be quite cheap, so I am not sure. and it can get very confusing about what determines the price.
This can be seen with these 2 Chen Zhengchu teapot that I have. The first called the 'Golden bell' and the second call 'Zhegu ti Liang'
I found retail price to both of these teapot at around $1800AUD for the 'Golden bell' and $1200AUD for the 'Zhegu ti Liang' which surprised me as I would have thought it would be the other way around. both have certificated.
if anyone one could give me any information on Chen Zhengchu and how popular he is please let me know, I have many more by different artists. such as Fan Xijun, Feng Yunhua, Wu Jufang and others, please let me know your opinion.