My husband had a vasectomy after my son was born...What is the best way to reverse it?

My husband had a vasectomy after my son was born...he is now two years old and I would really like to have another child around my son's fourth or fifth birthday. My husband is starting to consider the idea, but we are still unsure which way to go about having another child...Would we be better off to have him get a vasovasectomy and then ANOTHER vasectomy or should we consider In Vitro Fertilization or In Utero Fertilization? Also if you could explain the differences between In Vitro and In Utero...What are the risks or benefits ociated with each one of them? AND how much do each of these procedures cost typically? Thanks so much!