Will my child show up for kindergarten still in diapers???

I have been trying to introduce the concept of potty training to LG for a while now. The potty has had a presence in the house now for about 8 months, and she will occasionally even sit on it and read books...but that's about the extent of it. I have tried a reward system...I've tried "hanging out" in the bathroom with her for up to forty-five minutes in hopes she will go...I have tried Pull-Ups (which she vehemently rejects)...I have even tried letting her run around completely naked...all to no avail. When she finally realizes she has to go, she politely asks that I put her diaper back on and then proceeds to pitch a fit if I don't honor her request. There is a delicate line between making her do something because, dang it, I'm her mother and scarring her for life because I have forced this bathroom thing on her before she's ready. I am at a crossroads...
1. I am sick of buying ridiculously expensive diapers (for two kids) when one is obviously old enough to move on to bigger and better bathroom habits
2. She can verbalize when she is about to go, when she has gone, and when I need to change her
and
3. Because, dang it, I am her mother and I think she needs to go to the potty
Mike (of course) thinks I am overreacting...sometimes the "voice of reason" is annoyingly reasonable...and that I just need to let her do it in her own time. My question is...WHEN IS IT TIME???? They SO need a Parenting for Dummies book...