Never seen a pipe like this...looks a bit like a Falcon.

Somebody will chime in soon, a lot of them sold in the 60's, I forget the brand. Screw in bowl, sorta novel in its time.

Kirsten Pipe.
http://www.kirstenpipe.com/

They are back in business again so parts that need to be replaced and how to properly take the pipe apart is available on their site just Google Kirsten Pipe, they smoke great too.

banjo

They were patented before the Falcon. Interesting history to them and made in Seattle.

Make sure the stem and the valve on the front can be removed. If not, you have a job ahead if it can be loosened. Offer them much less money. They do smoke very nicely.
LRT

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!

The owner of Kirsten was very helpful to me a couple of years ago. I found one in an antique/junk shop and paid around $35 for mine. It needed new "O" rings so I found out Kirsten had started making pipes again and opened a shop near the Seattle Center (the pipes are made in the original shop in Bellevue, a suburb of Seattle). I sent her photos and she identified it as an early "Transition" model made in the early 1950s.
I've smoked both Falcons and Kirsten pipes. In my opinion, I like the Kirsten better because they body of the pipe is basically a big smoke chamber which collects the moisture and is easily cleaned. The Falcon has an advantage in that the bowl is threaded and screws onto the pipe body though. The Kirsten utilizes a hollow screw that goes through the bottom of the bowl.

There's quite a story seeping through this thread. The outfit is in Seattle, went out of business, and has now been revived. How often does that happen? With a domestic pipe maker. Falcon was bought and moved to UK. So this is the only domestic pipe maker in the US, probably. Quite a yarn as a backstory.