Picture posting is enabled for all :)
Since the highest 'cost' by far must be the cost of labour in these calculations, I would discount such economics.Should we add to the plus side of such calculation factors like for example gym membership fees saved, money saved as I could well have been out shopping instead of gardening, savings to the NHS because gardeners are a fairly fit bunch and so on.Every year in spring I see supermarkets offering rhubarb at 1.99 (reduced from 3.99 per kilo) and think to myself that I must be sitting on a goldmine. And have you seen the price of apples recently? At harvest time in England? There are no runnerbeans in shops and the tired looking things in plastic bags called runnerbeans are actually long French Beans from abroad. And when I think that I'd have to go to Harrods to buy some of the exotic veg I grow (if they even have them there ...) I am very lucky to get them so cheap from my garden and much fresher than I could buy into the bargain. And 'exotic' starts at snap peas and proper shelling peas, it seems, as neither feature in shops. The mangetouts are also flown in.Yes, the price of seeds and other gardener's needs is going up steeply, but a lot can be done or improvised to keep this to a sensible level.
Forget about feeding the family all year round, though. Your spuds will all be ready during the summer, unless you buy different varieties and stagger your planting, which will challenge the most enthusiastic beginner.