As mentioned I believe you are a little high but that is just an opinion. I will show what I would expect to be closer based on the searching I did most of the summer having sold a used sled and purchased a left over, so prices will reflect that. X or SP in the newer models is tough because of the limited differences unless its a T3.
Since we purchased a new left over 2016 163 for $12,000 all in a used 2016 should come down, a lot. Why spend $13,500 on a used when you can get a new left over. Options are limited but there were quite a few 153, SP, T3 and so on. You can get a brand new SP 163 T3 with estart for $13000 before rebates which is pretty good.
These are all starting points. I also won't go older than 10 years as at that point everything is worth something but what that something is can vary. From new you can expect $2500 less the following year. A lot of people get caught up in what they paid for something retail with all taxes and fees. Even though that is what they paid that isn't going to be flipped onto the next buyer.
2016 $11500
2015 $10000
2014 $8500
2013 $7500
2012 $6000 (non- XM) plain and simple a used XP just isn't as desirable as a XM
2011 $5500
2010 $5000 (non-etec)
2009 $4500
2008 $4000
2007 $3500 (non-XP)[/QUOTE
I would say that your prices are a fair starting point and actual sale would be a bit lower. Asking and selling not the same.
Carry over and economy are killing used prices.
Definatly a time to buy and get a deal!
Not a Cat guy but they also have some smoking deals going on.