We get through quite a lot of jam and marmalade here in the trenches and when I have the fruit available I like to make my own. I'm not sure that it works out cheaper than shop bought but I do know what has gone into it.
We had a marmalade crisis at the weekend, as in we ran out, and R has had to have honey on his toast instead, so that was top of the list. I buy the seville oranges in january, the only time they are available, and pop them in the freezer. My recipe works from frozen fruit which saves me from spending a whole week making marmalade in one go. The only bit I dont like is chopping the peel, I have tried doing it in the food processor but its just not right so I'll stick with the big knife.
Since I had to dig in the freezer I also got out some Damsons to make jam. These came from our own tree and we had a really good crop last autumn. Again I freeze them raw in bags then use as I need for crumbles jam or simply stewed. Damsons are easy to make jam with as they have loads of pectin and reach setting point quickly. The only fiddly bit is getting the stones out, the recipes usually tell you that the stones float to the surface and you can skim them off........ not mine they dont, I usually cook the fruit till they are all fallen to pieces then cool it and using a fork and my fingers fish out most of the stones. There are always a few remaining but that just proves its made from real fruit.
End result 11lbs of Seville Orange Marmalade and 14 lbs of Damson Jam. the store cupboard is looking full again.