I'm still holding on to my T5, just haven't gotten around to it.. Yes, you'll get a better deal selling it yourself.. Did you try looking on Ebay, Craigslist, or other similar sites?
For some owners, they'd rather not bother with selling it themselves.. Here in NYC, when I sell an important piece of gear, I sell it for cash only, with a signed written receipt, stated 'as is'.. I've sold three Tyros's, and all the buyers knew exactly what they were getting into it. I let them play if, or I play it, I point out any flaws, which at the most has been a scratch or something.. I also manage to have a 'friend over' at the time. Just in case some thinks of ripping you off.
Sad society has come to this.. Hence, the popularities of trade-ins.. but doing it yourself, can gain you more $$$$. All the Tyros's were roughly the same price as I remember. I sold them for about 60% of what I paid for them.. I look at all the for sale prices I an find, and price accordingly. I'd rather move them quickly..
There is always some fool, who thinks he can sell a 3 year old instrument for $300 less.