Majik,
870s have been around since dirt, the design is older than I am and I am getting pretty ancient (but not bad for a tree). And the 870 saw use as a riot gun _very_ early in its career, thousands upon thousands of them have done squad- car duty over the decades. Hard to offer reliable statistics, but probably more than 90% of current law enforcement shotguns are 870s. So no, 18" tube versions are not at all rare or unusual.
Check the left side of the receiver (i.e., opposite the ejection port) of the specimen at your dealer- if it says Remington 870P then $425 is not a bad price for a new one. PD trade-ins are sometimes available for half that much money from various dealers like CDNN.
If it really _is_ a Wingmaster (which will be so marked on the left side of the receiver) then someone likely stuck a riot barrel on an older gun. Check to see if it's for 2 3/4" shells only. If the serial number ends with an M it's a magnum action, and will handle 3" maggie numb shells- though this is no great advantage for most users, I hasten to add. New and used Wingmasters are a good deal more expensive than the current Express model but I dunno if they are offered with a factory 18" tube. The factory finish on a Wingmaster is a bright blue, BTW.
If it's an Express model it is overpriced by local standards, new ones are about $300 and good- condition used ones about $200 or less hereabouts. They are often available as a home defense version with an 18" barrel, sometimes with a factory magazine extension and no mag tube dimples. Some older Express versions will not have dimples, most do. Express guns have a matte blue finish and are marked 870 Express Magnum (or some similar variant) on the left side of the receiver.
Right now ALL the 870s at Casa Lapin are sporting their short barrels, there are two 18" Express HD versions (his and hers, the safe queens) with ghost ring sights, 2- round extensions, sidesaddles, aftermarket choke tube installations and lights on board. The two 'house guns' are set up to suit my wife, with 12 1/2" length of pull stocks, full length forearms, 4-shot sidesaddles, no mag extensions, mounts for a Streamlight M3 and factory 20" rifle sighted IC choked barrels with tritium inserts. There are a couple or four other Cinderella guns here and there, the Expresses that followed me home. One has a Mossberg manufactured 18" cylinder bore tube, the rest have 20" rifle sighted barrels. And there are my two original 870's, 1970's vintage Wingmasters with 20" bead sighted cylinder bore barrels. And the 'red gun' has a 20" polywhatever barrel too ;-) (red guns are lifesize solid plastic or resin nonfiring guns used for training).
Sorry, I don't have a digicamera. All my guns are camera shy anyway.
There is an assortment of long barrels (26- 28" barrels available for these 870s so they can all do multiple duty if necessary. The greatest thing about 870s is their durability and reliability, and the second greatest is their modular nature. It's easy to use the same gun for a multitude of purposes with a handful of parts, accessories, barrels and choke tubes.
I don't know prices in your area, so I can't say whether or not you can do better. It sounds to me as if shopping around some couldn't hurt tho. Don't be afraid of used 870s either, as long as you do your homework and check out the available examples thoroughly. After all, I can't adopt ALL the Cinderella 870s out there by myself...
lpl/nc
