Recently panickedthumb and chowda helped me get to Whimsyshire. Whimsyshire being D3's version of Diablo 2's cow level. Grinding for the items took an evening of solid runs on items but after a few hours I had all the gear to craft the Staff of Warding. It was nice of panickedthumb to walk me through the parts he had done as it was my first time in a game grinding for certain loot drops. Not too bad but you should expect things not to drop more often than they do. Or said another way, it can get tedious. The payoff is well worth the time spent though.

Oh and the total amount of money it takes to get the normal Staff of Warding is 150k. 100k for Wirts Cowbell and 50k blacksmith cost to craft.

If you want to get the Staff of Warding to open Whimsyshire I recommend doing the runs in normal and this helped me out quite a bit:

http://diablo.wikia.com/wiki/Whimsyshire

Mooooo:
http://i.imgur.com/o8Hao.jpg