Welcome to the Forum and I’m pleased that you like what you see. I’ve moved your question to a place that is probably more appropriate.
Weather stations come in a range of prices and features. Some of the things you need to consider are:
Features: Different units come with different sensors. Most (all?) systems have temp/humidity sensors. Some have an anemometer (for wind speed), wind direction, solar and UV sensors, barometric pressure, rain gauges. Some have shielding and fans for the temp/humidity sensors. You need to decide which features are essential, which would be nice to have and which aren’t needed at all. The more sensors you require, the more it’s likely to cost. Also if you want something like UV then there are only a limited nubmer of systems that support it.
Connection mechanism between the sensors and ‘console’: How far from your house/office is the greenhouse? Can you easily get a wire between the two? This will decide whether you need a wireless or wired system. Wireless tends to be more expensive than wired. Wireless sensors run off batteries and/or solar power, so you don’t need a seperate power source (you don’t for wired either).
Accuracy: Some systems might only be accurate to a couple of degrees centigrade and 1mm on the rain gauge. Others might be ten times more accurate. Decide how accurate you really need to be. For example, if you’re providing a formal public meteorological data service you need better accuracy than if you’re just doing it for a hobby. Just my opinion, but for monitoring your greenhouse you probably don’t need high accuracy. How accurate are your current thermometers…probably only accurate to a degree or so, which might mean you don’t need ultimate accuracy.
Frequency of update: Some units send data to the console more frequently than others. I think there’s one unit that only updates once every three minutes, which might be too long for you. However, updates every second might be overkill. Wired systems tend to update faster than wireless units and generally you’ll pay more for a system that updates more frequently.
Software: Do you want to connect the system to a PC? If so, the unit will need to have some form of PC connection, usually a serial port. Not all units have these! Some systems come with software, but as usual with ‘free’ software, it might not do what you need and you may need to buy an update to add the features you want. There is third party software around (for example Weather Display which supports dozens of different types of stations). Decide what you want to do…control things, upload data to a web site, view certain data on your PC screen? There’s a lot of different software to do lots of different things!
Price: They range from fairly cheap to very expensive (more than most people here can afford). The cheaper units aren’t abysmal though and if you want to dip a toe in the water to see how you get on, buying a cheap unit to experiment with before you decide on a more expensive unit might be worthwhile.
If you can give some answers to the above questions, I’m sure that the assembled masses will come up with some suggestions for you to look at more closely. I can’t comment too much on types of stations…I’ve only ever owned two, both Oregon Scientific (WM918 - wired and now a WMR928 - wireless). Both systems have worked well for me and I’ve never had a sensor fail in around 4 years of running both systems.