For the next version, the Apiary, Candlemakers, and Stoneworkers are notable cheaper. The Weaver's is staying the same since it requires Calendar to be really useful and the River Authority is designed to be expensive since it is very powerful. Boatyard is staying the same since lower the cost would make it overpowering for cities with more than one Fishing Boats.
I have been planning Fish Traps:
Fish Traps
+6% Food with Fish
+2% Food with Crab (crawfish)
+2% Commerce with Pearls (freshwater pearls)
+50% Production for Seafaring (there, that trait now has use on waterless maps)
Req: River
Tech: Fishing
Obsolete: Biology
I like the Sundial, but I would rename it "Primitive Clock" since water clocks existed. Here is how I picture it.
+2 Production (Reason you gave)
+1 Commerce (Non-laborers also benefit by knowing the time)
+1 Happiness (Reason you gave)
Tech: Calendar
Obsolete: Clockworks
The Root Cellar seems too powerful since the Villa holds 10% food. Pre-Modern cities would be growing like crazy with a Granary, Villa, and Root Cellar (Not to mention the Buddhist Palace, which holds 30%, that city would grow a population every five turns until the food tiles ran out).