mack - 2:01 pm on Nov 23, 2011 (gmt 0)
I am in a very similar situation. I have been in touch with the owner for several years, but at no point have I been able to convince the owner to sell.
I think I would tend to play it cautiously, without the mention of an amount. Simply inquire if the owner has plans, if they use it for anything. Then perhaps ask if they would be prepared to see it being put to use.
If you offer money early on, it becomes a sellers market and they can dictate a high price. If they realize they might be able to sell it to you and want rid of it it may be seen as a sellers market where you can offer a lower amount and it may be acceptable.