This is indeed a Kirsten. If you get it, I can help ID it. If the knurled, pointed tip on the shank won't twist free, getting it out may take some work. The early on es were metal-on-metal (and it's not threaded, just tapered) so old tobacco juices can gum it up; there are still ways of getting it free. The stem is the same, taper fit and may be gummed up. $19 is still a good price! Later models had a groove in the stem and in the end part (the "valve") with a rubber o-ring to prevent sticking.
The bowl will unscrew. The metal shank is hollow, and has fins to help condense the smoke, the gunky part remaining in the shank; the mouthpiece has a long, thin aluminum rod attached, with a hole partway along, to let only the non-liquid stuff get to your mouth. The rod acts as a ramrod when cleaning, like cleaning a gun barrel. The valve has a hole on one side; if you've smoked but can't clean at the moment, turn it until the hole doesn't line up with the bowl, and the gunk is trapped in the shank until you can clean it (it won't leak into the bowl and turn it sour).
Replacement parts that'll fit a model this old definitely aren't still available, BUT this pipe is most assuredly restorable!