there's always a small risk of impotence with vasectomy, and that's a risk we're not prepared to make.
The tubal ligation procedure is far riskier, more complicated, less effective (higher failure rate), more expensive and carries the later risk of developing a potentially life-threatening ectopic pregnancy. Two of my mom's good pals had ectopic pregnancies in their mid-40s years after being sterlised, and attributed their missed periods to the onset of menopause. One was even assessed for ruptured appendix in the ER. Both had to undergo emergency, radical hysterectomies. On the other hand, you'd be very, very hard pressed to find a man who's died from a vasectomy.
My dad, BIL and FIL have had them. All walked into the urologist's office and walked back out w/i an hour tops. No complications. BIL took Friday afternoon off and was back at work Monday morning business as usual. Far from making them impotent, it improved their sex lives as they no longer worried about birth control failures - you receive a letter when you are pronounced 'sperm free'. All are very, very pleased with their decisions and positively did NOT want to father any more children.
But yes, privately here and abroad, you can find a qualified surgeon who is willing to perform a sterlisation procedure on someone under 30. It is by FAR cheaper for the male, however, b/c he only needs local anesthesia and a VERY small incision. No laproscopes, no general anesthesia.