I wouldn't even think about throwing him a bachelor's party. You know how taboo that's in our society. I imagine this happening. A guy gets jealous because he was not invited, he goes home, tells him wife so-and-so is having a bachelor's party. No worries, the guy will also tell his wife NOT to tell anyone. She goes to the market and before you know it, the whole world knows.

If I were you, I would get him an expensive watch. Well, I am assuming people in Nepal still do wear watches. It is kinda going out of style here. And just to get on his wife's good side, get her a pair of gold earrings. All this is gonna cost you some money but you did say he is your best friend so it's all good. :-)