Test Sim had no traits that would modify price nor production rate. All items created at least 3 times and sold only through the inventory screen.
Here's the info I collected. I put it into a Google spreadsheet. Anyone should be able to view it by clicking the link:
http://spreadsheets.google.com/ccc?key=0Auo2LIjzxnM_dFNjRF9pb3AtbHlaT1VBMFpBMkw0OGc&hl=en&authkey=CLGzlJcGThe base prices are accurate. However, at least with the lower level items, I did notice small variations in price, but rarely. Only by $1 or $2 above or below. I thought the lower price was due to depreciation, but I made a bunch more and still saw the fluctuation without the day rolling over. No idea on the higher price. They weren't improved widgets since I wasn't level 5 yet.
There is a jump in production rate after level 5 inventing, for some widgets at least. It makes more of a difference the longer it takes to create an item. I did not do extensive testing. There may be another bump at level 7 and then every level afterward. I saw some reasonable variation in the last items. For instance, on one run my first miner after discovering the recipe, took 13 hours. Then another test after reloading the saved game, took 12 hours. But most took 9 to 10 hours. The main problem, is trying to get a miner completed while still level 7. 99% of the time I got to level 8 while making the first miner.
I may take some time at some point and track production rate at level 10 for all items. Handiness skill may also be a factor too. Mine was never over level 5 though. I was just more concerned with base prices tonight. Took several hours to get this much info as it was.