Subsistence farmers in the original home of the potato, do not buy seed potatoes, they save and use the smaller tubers from the previous seasons crop. That is what subsistence farming is.
The only reason to buy new seed tubers is if your original crop had a virus in it and then you could be continuing the problem.
Supermarket tubers have been treated to stop them shooting, but that treatment wears off eventually.
Which ever ones you use, the crop is determined by the quality of growth from the plants which is down to the amount of food and water the plants can get from your soil.
Our 'volunteer' tubers in the Polytunnel are just about ready to harvest,
Ummmm, I don't have that problem in my daleks. Maybe that's because I eat my potatoes, skins and all.
Fantastic...that's the way it should be...love to get something for nothing.
Many thanks Berghill...wont tell OH where his pots have come from!!...maybe next season...