When I moved into my new house a few years ago, I installed a bunch of outdoor landscape lighting.  I went a little nuts.  Front yard, back yard, two porches, an atrium, all-in-all over 30 fixtures that use these little G4 base 10w and 20w 12V bulbs.  I quickly discovered that these halogen bulbs are a lot less reliable than the 7w wedge base bulbs I had used before.  What is more, at around $6.50 for a two pack at the local builder store, they are also a lot more expensive.