Your first mistake would be trading your Apple Watch or any other Apple product into Apple. Their trade in values are absolute robbery.
Trading in through other sites and retailers would be too.
If you sell privately you would get far more money. In Canada Apple Watch devices do an excellent job at retaining their value. I sold my Series 2 SS when I got my S3 for $700 CAD. I bought it brand new for $950 and used it for a year. It was in brand new condition. I already have a buyer lined up to buy my one year old Series 3 SB SS with one extra sport band for $780 (it has Applecare+). It will be sold when I get my Series 4 Watch.
SS is the way for me, would never ever get the aluminum. Just my personal opinion, what you get for the extra money is worth it to me.
Oh I know about the "Give Back" nonsense, I leaned that the hard painful way on Sat! I traded in my S1 Sport towards the new S4. THAT was also a $25 trade in value, absolute stupid spur of the moment move and I simply wasn't thinking - mixed with excitement of actually landing a new one in a store. It is robbery from Apple..again my stupid fault.
I only saw AFTER I got home I could have landed $55 for a Best Buy GC, even more on other sites. Live and learn and yeah...the trade in of the expensive S1 Back SS...no way I would fall for that again.