I boil mine for 7-10 mins too, and I also have to soak mine in a vinegar/water solution periodically, because sometimes the minerals in the water will clog up my nebs (I use the Pari LC+). Once I've done that, they are as good as new!
I have 8 nebs, so when I am just doing my regular meds, I use 4 a day.
Andrea, I believe that the CFF has quit recommending the vinegar solution, because it doesn't kill all the germs we need it to. I will see if I can find the recommendations <img src="i/expressions/face-icon-small-wink.gif" border="0"> .