Personally, I do not like outdoor wood furnaces. Go to this forum for more research:http://www.hearth.com/talk/categories/4/
The price you mention sounds high to me for the age.
Three very important things to consider -
1 - how much life doe it have left? It could be on the way out or it could have a few years left on it. Don't count on these type of stoves lasting a long time. How did he care for it?
2 - Why is he selling it? Could be he found out that it isn't very efficient.
3 - Can you install it legally? Check local and state codes. Both NY and PA have strict laws now regarding the installation of OWB's. Many local codes have banned them all together.
I burned wood up until this year. My supplier said his best customers were the people with outdoor wood burners.