TN Hilbilly
The costs will vary depending on what weather station you use. I use a Davis VP2 which is pricey - $500+ but it is top of the line with many accessories like additional temp sensors. I have the wireless version with a rain gauge/temp sensor in my back yard and separate anemometer (wind) on my roof.
The software I use is weather display
http://www.weather-display.com/index.php which costs $70 with lifetime updates free. It is GREAT software and has an extensive user community for support and help -- much like the Pond Boss site with great people willing to help.
There are other weather stations which are less expensive. The key is a weather station that can connect to a PC. See the list of stations that Weather Display supports at
http://www.weather-display.com/supported.php Other costs would be for a web host if you want a public web page and a PC. I have a separate PC dedicated to my weather stuff. I bought a cheap open box PC at BestBuy for $400.
Feel free to send me email if you want to talk more.
Frank