They still sell them though. Any sporting goods place or general purpose store with a camping section, or outfitter such as REI will sell you one for $8-10. This struck me as a bit expensive for something so simple. I did some looking around, and it turns out that Harbor Freight, the cheap tool store has them for less than $3. That's cheap enough that I'd buy one for my hiking pack, one for my car, and one for my car camping supply bin.
They come with a little serrated striker tool. At first, I appreciated that, thought anything that saves my knife from wear was a nice inclusion. But in today's field testing, it didn't really hold up well. Yeah, you could make sparks on the flint strip, but it was awkward to hold and didn't strike them very well. It also sucked at trying to bite into the magnesium. Actually, everything I brought today had a hard time with that. After giving up on the little green striker they included, I tried a small multitool I had with me, figuring it was better to wear on that blade than my good knives, but even that proved difficult to strike good sparks from. It didn't want to shave off much magnesium either. Finally, I just gave up and resorted to using my Buck Pathfinder 105, which worked far better than either of those. I should have just used that to start with.
Fortunately, the dried beech leaves we harvested to catch our sparks caught very readily, and the magnesium part wasn't necessary. Now, I could swear that the block I owned two decades ago gave up magnesium very readily. I'm not sure if they changed to a harder material for all the firestarters, or if it's just the cheap harbor freight ones, but be prepared for the magnesium to be very reluctant. it may take some time preparing before you have a pile ready to catch sparks. Or bring some dryer lint instead.
Despite the very solid, even reluctant, magnesium block I would in fact recommend these. It's hard to beat that price.
Starting the fire:
Clearing at Plamann Park where we built our fire:
Boiling some water in my snow peak pot:
Available from Amazon.com or at a local Harbor Freight Tools.