I am with you on this one........I spent a bit ( ) more than 2K on mine/my wifes. haha

On the other hand, I would say get what you can confortably afford. IMHO it is just crazy to go way beyond your means on a ring. Sure you are going to have it forever, but to put yourself in a bad way (i.e. spend to much) is not the right way to "start" a marriage. She is going to love whatever you get her - especially if it is a surprise. And you can always get a new diamond at a future point (i.e. anniversary) and make the old one into say a necklace or something like that.

Edit: I have always heard about the 2 month rule - never heard about 3 months