I know this is a little off topic, but I don't know where to ask. I'm looking for a used greenhouse - a big one - within 5-6 hours of Lubbock TX.
The "proper" place to post this request would be the Garden Exchange Forum (see below). You might also try the Exchange section of the Gardening in Texas Forum.
Here is a link that might be useful: Garden Exchange Forum
Another place you could try looking is "craigslist" in your area. I've found great deals on everything you could imagine!