I tried to find info on that older CT12K mentioned above at the surplus shop. It was impossible to find if it is there as there is no search function at the site. Reading up on it, it has accuracy to 3000ft.
What can the CT12K handle?
Also, what type of home station (or Airport AWOS) are you running at home?
It seems like their would be a good market for high end airport surplus, but I did not find anyone out there on the Internet.
Per the manual:
Range: 0 - 12,650 feet *1
Resolution: 50 feet
12,000 feet aquire: 30 secs max *2
*1 NOTE: In air traffic systems, the maximum reported value allowed is 12,000 feet.
*2 NOTE: This is for the "instantaneous" cloud height. In air traffic systems, the minimum average required is 20 minutes.
At most, 2 cloud layers can be reported by the CT12K.