For me, i think the key is to sell the previous models soon after the new models are out. Many people don't want to try a brand new model and will still be looking for the older model. After the new model has been out a while then the price you can get for the older model goes down. Plus if you've increased the storage capacity or have an extended warranty it also helps with the resale. I sold several of the Series 3 on ebay soon after the S4 models came out. I pocketed 80% to 90% of what the lifetime Premieres(non XL) cost me since they had also been upgraded to a larger hard drive years ago. And I sold my two tuner S4 boxes when the Elite came out. I sold some here at tiVo Community, although I might have sold one or two on ebay, I can't remember. Since each Elite I was getting had four tuners which was replacing two, two tuner, Premieres. I wasn't trying to get an exorbitant value for them. Plus when the Elite first came out, the resale on the two tuner Premieres was higher than it is now.