Hi Bob,From bulbs.com:
http://bulbs.com/products/product.as...ucts&class=875
JCD12V5WH20 Light Bulb
Product Number: W-JCD12V5WH20
Specialty Brand 5W, 12V Halogen Capsule Lamp with G4 Base, 2000 Hours Rated Life, (0.36 inch / 9.0 mm diameter, 1.22 inch / 31.0 mm length), 2900K color, Sold Individually.
1.98 a pop currently, 1.78 for 18-26.
I had the same idea about mixing them, but once we saw how little difference they made in light level, I just switched them all out. YMMV.
By my measurements, they consume just a little less than half of the 10W bulbs.
Good luck!
j