I think part of the price of the Davis goes towards the modularity and the add ons. But as one person pointed out, over a hundred bucks for the interface chip? Sheesh. Arduino has a whole boat load of interfaces on board and a computer, too, and sells for $30.
As a slightly different slant, I would like to see simple set up and interfaces to allow the interested beginner to set up a reliable station quickly and have fun, perhaps getting bitten by the Wx station bug and doing more. We used to have systems in schools around here. Other than not seeing them or hearing about any science promoting education any more, what sign do our educators give to our children about being aware? We used to have a 'team' that raised the flag, while another team read the temperature and barometer and recorded them in a log and graphed them. Even the non-nerds were involved and I think were subtly encouraged to be aware.
Yet I know I'd like to have a proven accurate temperature measure, such as a really good quality glass thermometer. Then the ability to get a wx program or very configurable station, that would allow me to build a table that for reading "x" from the station, that the measured real temperature is "Y" and display and report that value. Same with humidity. Sort of like the look-up tables you had to make with Campbell Scientific stuff. But while I might futz with that for a few months or year to get a range of readings and tweak it over time, who in their right mind as a teen ager getting a station for a birthday or Christmas present would want to go to that length, or what difference does it make?
Site to site variations really make a difference. Watch your car thermometer as you drive hilly country to see two or three degree changes on the road. Yet a portable reliable standard thermometer is a must. We have one radio station in the area that for years was five to seven degrees colder every winter morning than even the neighbors with good equipment or the surrounding stations (when they really had stations and didn't just read off the AWOS or airport temps. I think they fudged it just to be the most extreme. So we do have confusion as to what is accurate.
Are glass mercury thermometers linear across their whole range any more, or are they just close for the ten degrees on each side of their certified temperature?