I think perhaps the biggest cost contributor is your mixed diet household. If you have all of the family eating packaged/processed food, nibbling on SCD food and just you eating SCD and trying to make mixed meals then you have to buy almost double the groceries in a way. If it's just one person (a single person) like myself then my bills SCD vs. Reg are equal. I just replace the cost of packaged food with fresh food.
Hope that makes sense, but I think that's your biggest cost contributor. Maybe try budgeting ~$100/wk for "your" food separately. Put it in separate area in the fridge/freezer that no one eats but you and plan your meals I think you would find things work out the same.
Also, frozen veggies or even organic frozen veggies can be inexpensive compared to fresh. Organic pasta sauce, with frozen veggies and spaghetti squash can go quite far and be very filling on a budget.
Just get's boring eating the same thing over and over... that's what I hate.
EDIT: Maybe the above doesn't make much sense, but after roughly 7 years now on SCD or Palio type diet my grocery bill is the same as it was prior. My fridge and cupboards look a lot different though. Friends come over and say - What the heck do you eat? or Don't you eat? after looking in the fridge. It took me a while to clue in that there's no packages of stuff.... so they can't figure out how or what to eat cause they would have to actually ummm make something from scratch. It's kind of funny in a way. I look in and see a weeks worth of food and snacks. They look in and scratch their head...
Post Edited (Canada Mark) : 6/15/2014 9:39:37 PM (GMT-6)