I've spent entirely too much time trying to figure out what to research next, whether a certain trade is a good deal, which techs have trade goods, etc. I finally got fed up and did something about it. I've put together a tech tree (based on Javascout's tech tree) that includes the tech tree, the price of each tech, and whether or not each tech has a trade good, wonder, achievement, super project, or mining module associated with it. I believe the price of tech varies by galaxy size, but the prices should be relative when trading.
It's saved in a .xls format so you can easily modify it to suit your preferences. It prints out nicely on two letter sheets. If you come across any errors, let me know (I'm sure there are a few in there)
Hope this helps you as much as it will me.