Scarlet-Tech
Again, If you are willing to trade, you are willing to sell. It is the same thing, and anyone trading from a 980ti to a 690 would be a substantial downgrade (not a side grade as they would lose 4gb of VRAM allotment), which would be a limited crowd that would jump on that.
 
Buying a brand new 980ti would also be a good idea to get the full 3 year (or option to extend to 5-10 year) warranty.  At this point, you can see that a valid warranty is a good thing to have. That would require you to sell something though, of course.  
 
If you do trade, be aware that some companies, like NVidia themselves, do not offer transferable warranties, so the person you trade with would need to run your RMA if anything were yo ever go wrong, and there are other companies that do not allow the coolers to be removed for any reason, even just a TIM refresh.  I am giving you this heads up so that you know which companies to research and watch for, so you don't end up in a predicament where you have a paperweight.  At that point, even the CEO/President of Nvidia isn't going to help, so make sure you do your research ahead of time.