Microwave popcorn is convenient for traveling or keeping at work, and fairly cheap as a snack. If you are staying in a hotel, you may be able to pop it in your room, or the hotel may have a breakfast room with a microwave they'll let you use. I buy Trader Joe's 94% fat-free single-serving packs (a pack makes about 3 cups, which is a serving), which come in a box 6 for $2. I think 33 cents is pretty reasonable for a snack on the road or at work.
But at home, I have been popping my own popcorn on the stovetop in a little canola oil. I buy bulk popcorn for under 80 cents a pound, so even though the microwave popcorn I buy is reasonably priced, bulk popcorn is a steal. Even if you buy supermarket brand bulk popcorn, you probably won't need to pay more than $1.50 a pound, which is still a great deal. Depending on how big the kernels pop up, I estimate that a generous handful of unpopped corn yields about 3 cups, and you need about a tablespoon of oil for that. (But a lot of the oil is just for coating the pot - you're not eating all of it). After popping, I salt it, shake it around to distribute the salt, and put it into a bowl. It's also good with a couple of packets of Splenda sprinkled on it - very much like kettle corn. As a snack, this is a real bargain - you could serve your whole family popcorn for under a dollar.
I was afraid the corn would burn, but I've found that if I shake the pot occasionally, and turn the heat off when the popping slows (one pop per 2 seconds or so), it doesn't. Also, I add the corn to a cold pot and shake the kernels so that each one gets some oil on it.
I've decided to get a microwave popper, though, to free up the big covered soup pot I always use. (It's cheaper than buying a second soup pot!) Here's a picture of the one I'm getting, which costs $13:http://www.amazon.com/gp/product/images ... &s=kitchen
These poppers were really in vogue 10 or 20 years ago, so you might be able to pick one up at a garage sale or thrift store.