Building a weather station and observatory sounds like a dream project! Reminds me of when I set up a small weather station in my backyard. It was so rewarding to track the weather patterns and observe how they changed over time. If you're looking for quality equipment, I highly recommend checking out Ambient Weather ambientweather.com. They have everything you need to get started and their products are top-notch.
What I'm most surprised about is, (after I set up my own weather station) - Is that there is ALWAYS a difference in what I record, and what the is officially reported by the government meteorological office. Also, whenever I now try to predict the weather, by my own readings and checking with weather satellite images - I to my own astonishment, am now unbelievably accurate.