Value algorithims and another "Is this a good deal"?

[woodlandcottage]

I live in the mountain region and have been seriously looking for a 2619 or 2720 TM for several weeks now. Casually looking for a few years before that though. Anyway, The Car Show is a well known dealership and we have been there a couple times, but I thought their trailers were overpriced. The used market isn't too much better in this area. I saw a 2002 this weekend that was filthy and falling apart and priced at $8K. I'm not sucker enough for that!
But anyway, I know NADA guides aren't the end all be all with TM, but a reasonable starting point. Here's where I'll get to my first question, or rather, several questions about NADA values.
I'm about to drive an hour away to see a 2009 TM. The asking price with all the options is actually at the NADA average retail. This is a private seller. But I wanted to get an idea of how NADA calculated the drop in estimated value by year so I calculated the NADA for a 2011, '10, '09, and '08 with no options in the model we're going to see. What I found was that the average value of a 2011 was 66% of list, 2010 was 57% of list, 2009 was 53% of list and 2008 was 41% of list. Now the 2008 had a list price of $2K less than subsequent years but I calculated the 41% from the lower value. Now, that scares me a little bit so I tried the same calculations with another model. The algorithm/percentages were the same. I realize that the value of something is really what someone is willing to pay, but there has to be some reason the NADA shows such a significant drop in a six year old model. What could that be? If I were to buy this TM at the 53% value, can I expect it to drop in value by 12% of original value in the first year I own it? That seems to be ridiculous. It would represent a loss of $3K in value in one year. Of course, we plan to own our TM for 10 years but who knows? We may need to sell it and I wouldn't want to eat a loss like that. And that brings me to my next question, since the 2014 models will be released this week, does that now make a 2009 a 7 year old model? Would I be able to use that fact as leverage to ask for a lower price, even a rate of 41% of original price? Thanks so much in advance for any help with this!