I paid $4000 Can for an '02 WR426F, with a small tweek to the right hand side of the bars, a couple of extremely small scratches and a small portion(and I mean small) of the paint rubbed of the the shifter side of the frame from boots.
When I was looking a guy from Maine had a 01 YZ426F for a round $2000 US and it was mint!!! I think it was priced low because he didn't have the market there to seel it! It depends on what you want the bike for?!?! A WR will not make a "Great" MXer and a YZ will not make a "Great" Enduro or Dual-Sport. If you look in the classified section, I'm sure you will see that the YZ (as there were MORE of each year sold) are valued less than a WR. The real question you have to ask is... Do "I" want the bike and Do "I" think that it is in "Good" enough shape for the price he is asking? $3800 is not too bad if it is in mint shape for a YZF. If you weren't so far out on the East Coast, you may be able to get the same bike for quite a bit less!!!