Exploring: Worth it?... Are there any things [of] actual value?
I stumbled across an
incredibly extensive analysis of artifact exploration at SoaSEWiki.com. Including an :
overview here, and an extensive individual
artifact appraisal hidden away here.
The bottom line is: On average, exploring
does (barely) pays for it's self over the long-term. Especially if you find the "Data Archive" artifact (middle one on the bottom), which reduces all research costs by 25%. It is by far the most valuable artifact, more than twice as valuable as the next.
But, first level exploration (45% of the total cost)
does also reveal many other planetary bonuses. At a minimum, it is probably always worth it.
Don't forget the SP
cheat, that I mention above. With it, you can just research those planets with artifacts indicated, and save yourself a ton of money