I would think its safe to say sell it for $400.00
Even if its pretty much brand new, people would rather spend $18.00 more and get ti with free shipping brand new themselves. You gotta give someone a good deal if you want to sell your personnel gear, even if it may be brand new.
Just a question, why did you spend 2.5 hours seam sealing a new tent, it shoulda came sealed? I got a trango 2 and had it for 3 years and it still doesn't need to be sealed, and Ive used it quite a bit on Denali, Rainier, Tetons and in the Whites and Dacks.