I love the idea of NFP too...but like you I don't want to get pregnant again--and ESPECIALLY not an unplanned pregnancy. In a few years, there is the slightest possibility that we may want another one. But if it happens, I want it to be a decision rather than an "OOPS", since we already have three kids. Financially we are OK but it's the emotional resources that I'm most concerned about.
Anyway, my husband is going to go and have the vasectomy. Now it's just a matter of getting him there!!