I too found that at first I spenta lot more on groceries than usual. However as I've settled into this WOE it's really evened out and back to what I used to spend. I'm never hungry, and eating out is easier.
As to Jenny Craig, I've never tried it. I have tried many others with a variety of results. (I once lost 30kg/66lb on weight watchers) JC may be cheaper but did you keep the weight off?
Icertainly don't know all the answers (just look at my stats!) but I'm giving this a jolly good try and hope that it's a life time answer not jst another fad.