Before you purchase the trailer, I would suggest you try towing it with your Envoy to see how it handles and to make sure it does tow the trailer with no problems.
Your Envoy's tow rating (2003 Envoys are rated at 5,300 - 6,200 lbs depending on 2wd / 4wd & gears) is greater than the GVWR of the T-1950 (which is 5000lbs), so it should tow fine, but it's always nice to test it before buying. The dealership should be willing to set you up with the proper hitch to test drive / tow it.
As Jon mentioned, the price seems a little high, plus missing the chair, you have room to bargain.
Mary & Tom (aka Hutch)
2015 Jayco Eagle Premier 361REQS
2014 GMC Sierra 3500HD 4x4 CC D/A
Sunlines: 2005 Solaris T-280SR; 1999 Solaris T-2670; 1998 Saturn T-24A