I really like the new Nexus 9 but have a Nexus 10 that works just fine. Is it worth selling the N10 and picking up the N9 for $399? If so how much is a reasonable price to sell the N10 for?
I'd say, go for it. While the 10 will get Lollipop, the 9 is an upgrade in pretty much every respect. Its got a faster processor, better screen I believe and more compact with slightly smaller screen but also less bezel. Not to mention lighter...
I suspect resell value is pretty low. They had a sale on them a few months ago for around $150 for a refurbished unit. You can check Amazon or other sites and see what they will give you. Or go to ebay and check completed sales. Don't forget to subtract the fees from eBay.