This batch of jam cost me $5 (including pectin and sugar), and I made 48 ounces. It's so much fun to make and it takes around a half an hour, start to finish, as long as you remember to run the dish washer so that your jars are nice and clean and hot when you go to fill them. Note that I'm giving you directions for freezing the jam, which is a great baby step to take if you're new to canning. You can put the jam in jars or plastic containers and pop them in your freezer, and then you don't have to get into the whole sterilizing/pasteurizing scene. Just be sure to wear an apron, for the full Ma-Ingalls effect.
I use no-cook or no-sugar pectin, even though I both cook the jam and add sugar to it, because then you can cook it for a shorter amount of time and add less sugar. I can vouch only for the three pectins I name here for this method; other kinds may work fine, but I don't know. Depending on where you live, you may be able to get large quantities of imperfect fruit at rock-bottom prices, and this will have the added benefit of producing a locally grown jam. But you can also buy fruit at the supermarket, if you're eager to experiment. It's a fun cooking project to do with kids -- just be careful because, as my mother likes to say, nothing is as hot as hot jam.
Yields 5-6 half-pint jars
Prepare the peaches: cut the peaches in half and remove the pits, then use a citrus juicer to ream the flesh from the skins, mashing it up as you go (this is a great job for a child). Don't worry if there are some chunks of fruit or bits of peel. Alternately (this is the traditional method) you can bring a large pot of water to a bowl, drop the peaches in for 1 minute to loosen their skins, plunge them into ice water, peel and pit them, then finely chop them and mush them up with a potato masher.
Measure 4 cups of the peach puree into a saucepan with the sugar and lemon juice, and bring it to a full rolling boil (the kind you can't stir away) over medium heat, stirring occasionally at first and then frequently as it gets hot, and then constantly. At various moments you'll think it's boiling, but then you'll stir it and it will stop boiling, so you'll know it wasn't really boiling yet after all. You are not looking for a tentative, waffling simmer here. Boil for 1 minute. Now add the pectin and cook, stirring vigorously, for 3 more minutes (ignore the no-cook directions and sugar amounts on the packet). Turn off the heat and stir in the almond extract.
Ladle the jam into scrupulously clean jars, leaving an inch of headroom for freezer expansion. Cap them and, when they're cool, let them set up overnight in the refrigerator before eating. Eat within a month or freeze for a little midwinter sunshine.