Kids cost a fortune, but are worth every penny. My 3 kids are pretty much my wife and I's entertainment in that we spend most of our time doing things with the kids and going to kids events. I'm not sure what we'd be doing without them, but someday I guess we'll find out.
My best guess is we spend 30K - 40K total per year on our 3 kids (not including college). According to Quicken, we have spent a total of $11,377.78 on our kids in a little over 4 months (excluding college). This is for a 19yo, 16yo and 9yo. We spend a lot more than some parents we know. We also spend a lot less than others.
My 19yo college runs right at 17K per year (state college - mid-America). So, including college expense, we're looking at probably 50K per year for all three.
My guess is I would be easily retired by now without kids (48 years old). I plan on retiring at 58, so I guess that means my kids cost me 10 years of retirement. Worth every minute.