At the recommendation of my friend Mrs. Mac, I looked into Tattler reusable canning lids. They are food-grade white plastic lids combined with red (silicone, I think)* gaskets. You use standard bands to hold them on, and I have tons of those. Now these things are an initial investment. Including shipping, they are roughly 70 cents per set. BUT the payoff comes in that they are supposed to be reusable indefinitely, like many, many times. Years and years. (I saw some comments on a blog saying that the gaskets have to be replaced each time and that's not true, as long as you don't lose them down the garbage disposal.)
I'll say right now that I am very happy with the lids. I used them to make quite a bit of jelly this summer and had a 100% seal rate. My initial experience was not so happy, though, as I pressure-canned a lot of beans (refried and baked), and had a failure rate of about 50% on the seals. I was so mad I wanted to return the bunch of them. But Tattler's customer service is excellent; they encouraged me to try again and to make sure I was leaving adequate head space. I am guessing that's part of what I did wrong, I fudged on the head space. Also the instructions tell you to hand-tighten the bands and then back off about 1/4 of an inch. I think I backed off too much. Being more careful about these things, I did great. I still need to pressure-can something and make sure that's not really a variable in the equation.
One final caveat is that if you share your canned goods, you may want to use partly the old lids and partly the reusable ones, so that you have some to give away without losing your expensive lids.
* Correction: Rubber. I just checked the site again and the gaskets are rubber. Now that's a concern, as rubber will break down with repeated heatings. I guess that's why they sell spares.