What is the value of a 1907 D silver half dollar in very good condition?

The term "Very Good" (with caps) has a specific meaning in numismatic grading; it actually means a coin that is just above the lowest collectible grade of wear. If that's what you're referring to, Numismedia quotes a 1907-D Barber half at $13 (retail) in VG.

If you're using the term as a generic description, that might be closer to VF, which means slight but obvious wear. In that case the coin is quoted at $79 retail, so you see that the meaning of the term is very important.