Agree that it is too much money. My son just bought a '96 YZ-250 for $1600, included a spare (new) pipe, a couple extra sprokets, new brake pads (still in blister pack), and a few other spare parts. Tires were in really good shape. He picked it up from the guy and hauled it out to the desert for the Thanksgivin gweekend and has been just pounding that bike since.
The new tires are certainly a good thing, IF they are appropriate tires for the terrain you will be riding in. The tires look like great rock tread, but there is snow in the background of the picture so I am wondering if mud might be a bigger issue than rock.
A new "top end" is not a selling point to me. That just tells me that it was ridden hard and it seized, unless the top end was just new rings to freshen it up a little.
New plastics, new handlbars: Tells me he crashed. Okay, maybe not, some people have a preference on the bar bend and don't mind spending a couple hundred $$ for their choice of plastics. Check the radiators though, make sure they aren't smashed in.
Check the areas that you might like to ride and see if a spark arrestor is a requirement. Having an aftermarket race exhaust is not an advantage if you get turned away from areas you might like to ride.
Overall, a YZ-125 is a great bike and from the picture it looks good, but I think the price is a bit high.
Rod