Need some advice on a plow purchase

First, parts availability. I�ve searched the Archives and have been following the Implement Alley postings for about a year now. I get the impression that repair/replacement parts may be difficult to come by for the Dearborn or Ferguson plows. I�ve not seen much information on the International. Since the Tractor Supply plow is newer, I am assuming parts will be available, but the plow will not be as durable. How difficult will it be to get parts for Dearborn or Ferguson plows?

Second, what should I look for in the way of problems or likely missing parts on the plow? The plows I�ve seen don�t seem to have too many moving parts. I suspect most problems will be from wear. Seems like the points are the most subject to wear from what I�ve read. Any advice on a pre-purchase checks would be greatly appreciated.