You can take cuttings from the side shoots of tomatoes. They will grow roots in water, but better is in really mushy, wet compost, water roots are different from soil roots. Put a cutting in a polystyrene cup with a hole in the bottom and then floating it in a larger cup, works fine.
Special tomatoes are dear, but they always offer them for sale earlier than they should, so I think I can run to one each of a couple
