I remember seeing someone demonstrate that with celery, at least, it was actually more efficient to just grow more from seed, but I guess that depends on your individual success with planting seeds!!!

BTW, something else to try if you have an outdoor garden this year... tomato plants can be overwintered inside!!! Take cuttings like you would from many other plants and root them. I kept them in milk jugs when I tried it. When they get too big, either repot or take more cuttings until you're ready to plant them out in the spring. Especially good if you've got some heirlooms that you want to keep going. (Of course, the seeds are easy to save and easy to plant anyway...)