I don't think you will save money because the point of organic is not to be cheaper. However, if you are ruthless about planning meals, using every last scrap of veg and not eating much meat, you can do it without breaking the bank.
I've used Abel & Cole for years now and have had very few problems, and the couple of times things went 'wrong' they sorted it out so quickly, efficiently and 'nicely'. Otherwise, the quality is good and service efficient.
We now have a combination of food-buying strategies:
allotment and garden which sometimes keeps us almost self-sufficient and at other times of the year only supplies a very little
Abel & Cole - order every week. We don't have a box at all now (partly because for much of the year they're sending the same stuff we're growing!). Instead, we use them as almost a supermarket shop. We have some regular stuff every week, mainly fruit and few basic veg, then top up with whatever else we want. Don't forget, organic stuff includes 'cheap' things like pulses, so I often add in a bag of lentils or whatever. Cheap meals like that really offset the more expensive items.
Farm shop once a week - we get nearly all of our milk here, lots of fruit and veg and a few other staples. Their prices vary - some things are really good value, others more expensive.
Independent fruit and veg shop in town once or twice a week. Very good value but no organic and little local/UK stuff.
Farmers' market in town once a month.
Health food shop in town 3 miles away once a month or so - great for staples like pulses, flour, grains, dried fruit etc. They also do refills of things like washing up liquid.
And about every 4-6 weeks we have to give in and visit Sainsburys for the few things we really struggle to get elsewhere!