That's well over-priced. I have an NSR250 MC21 that cost me some $2,000 or so....OK granted it wasn't in the same condition as this one and had a fairing that was pretty tired and general ageing, etc. it was only a project base, for which I essentially only needed the engine, electrics and a few other bits - the rest's been sold as parts... Or will be when I get around to it...
It says 1992 on the ad, but I'd bet it wasn't manufactured in '92. That looks like a '90 to me but I haven't checked into 1990 styles, the later ones didn't have this colour scheme AFIK. Here's a brief history of the MC21 for those that may be interested:
http://www.nsr-world.com/history/
On this bike a repainted original fairing, new exhausts & expansion chambers from Tyga, polished forks, etc. tells me this bike probably hasn't always been in such tidy condition. Tyga has recently started supplying Ohlins shocks for these, which is probably where this one has come from. I notice some low spec. Brembo calipers at the front, along with rusty floating disc rings, Tyga rearsets, a steering damper & what may be a white face instrument conversion from the single pic. There may be more, but it looks like it's just got a few inexpensive Tyga bits. Missing the passenger seat pad, which usually distorts from much time in hot sunshine. The front cowl frame has been painted black, presumably because it wasn't in good shape. It's not an original bike...
Since buying mine, I've put it away whilst collecting a lot more parts and should be beginning to assemble on an MC28 frame (With title), single swing arm, etc. along with a long list of top quality parts & upgrades over this winter... Tyga's making a full carbon MC28 tail cowl from a mold produced from original panels sent to them along with a GP replica top cowl complete with carbon ducts to go with other MC28 original bodywork & tank which they'll paint in Doohan GP replica colors before sending to me. Right now I have all the bits to assemble the bike so it'll run, only missing things like brake lines which I'll but components for & assemble when the measurements are in hand.
In the end, I'll have a perfect MC28 with sorted suspension, brakes, etc. but without the difficult to de-restrict MC28 ECU & silly credit card key - complete with Dymag Carbon wheels, reworked (Maxton 20mm cartridges) NC35 upside down front end with larger brake diameter, etc. all done - for less than the cost of this near standard bike that's been tarted up for sale. Should be fun with around 60 bhp, modern suspension, brakes and tyres.
A mint MC21 is about $4000 in Japan, maybe a little more for something really pristine, or $6,000 for a tuned one. MC28's are the holy grail of these and worth a bit more.
Hell, if someone here really seriously wanted an NSR250 in N. America, I could buy one here and send it to the US in about 8-10 parcels, via post. No idea on how it would be registered, but it's possible I guess. People have done it before. They're pretty light, so broken up into parts it's feasible, especially using surface post it's not that expensive. I've already sent an engine to Australia in the post for an enthusiast there. I'd just need to be paid for the time put in to make this happen but it would be a helluva lot less than $14K!
These classic 2 strokes are gaining value, but the only 250's reaching over $10,000 in Japan are mint & as new last of the breed MC28's and even those don't usually go much above $8,000 for the best examples. Has to be something truly exceptional to get to $10K. I've seen a highish mileage NR750 sell for $25,000, or RC30's sell for $17K here, so $14K for an MC21 NSR250? Nah...

I know someone with a mint MC28 in original Repsol colours that's been hiding in a garage for years too... Unfortunately I only found this one after I'd bought mine, but anyways...
Euro RC51 SP2: HRC WSB Ti Hi-Level, T1 Airbox & Snorkel, PCIII, Dymag CA5 Carbon Wheels, Ti64 Spindles (F, R & Swing Arm), Mori Link, Maxton GP7 Shock & Ohlins 832 Forks, Brembo GP Calipers & SBK narrow track (F), Braketech Disc (R), Brembo billet Underslung x 2 Brembo RCS, Tyga Triple, 7075 Stem, Probolt Titanium all over, Babyface rearsets, MR Complete Carbon Lineup, Custom Undertail & CBR 1000 LED, Watsen LED Indicators, Harris Brace, Giles clip-ons, Corbin seat, etc. 2013 BOTY.