Depending on your capabilities and what you want to achieve you can do a lot with 1-wire for not a lot of money. My system is pretty elaborate, weather, solar, temperature sensors throughout my house from the freezer to the attic. I just have one humidity sensor inside which I believe to be fine for my situation.
I use OWW for reading my sensors and passing them to misterhouse via socket programming. I use the data to control fans and lights. I also store the data in a MySQL database for historical reference and use RRDtool for graphs on my web page.
If I had to do over again, I would bite the bullet and by a Davis weather station. I would still have some 1-wire temperature sensors since they are so cheap, around $4.50 each.
My 2 cents worth.