Base gasket leaking

I am considering the purchase of a 2009 TW200 with 1800 miles on it (seller says these are all street miles). I have been reading on this forum about the problem with bad base gaskets on these bikes until the 2010 model year. Any ideas out there on about what percentage of the pre-2010 bikes have had problems? How much should I be worried about this happening on this bike? There is also a 2010 available for $400 more than the 2009 which he is asking $2900 for. Are these fair prices for these bikes both in good condition? The 2010 was used in safety training and has 238 mi on it. One more question, I have seen some say here that the quality of 2000+ year model bikes has declined when compared to the TWs made in the 90's. How much of an issue is this? Thanks