My advice, for what it's worth...
Learn the history of the stadium you're looking for prior to the purchase. For example, there are several varieties of Yankee Stadium seats available. Straight back seats come from the original build in the 1920's. In the 1940's they replaced the free standing folding chairs in the box seat area. The replacements were curved backs and seats. And then there are the plastic ones that went in in 1973-1975 and came out this year.
Refurbished vs. Not??? - Tough question. Purists like them "not". But some of us have to live with, or be married to, non-purists. I have a Yankee Stadium seat that was refurbished way back in 1973, and not touched since. My wife allows it, grudgingly, to sit in my office, right inside our front door. I also have a double seat from the Boston Garden, unrefurbished. It can't seem to make it out of my garage.
Here's some sites to look at:
http://yankeestadiumseats.com/index.html
http://collectiblestadiumseats.com/
(these two are the same seller, just different sites.)
http://www.authenticstadiumseats.com/index.html
Here's mine.