Vick,
The way I do it is by removing my discomfort with the idea of dealing with the hassle of selling.
Most people love the idea of buying low and selling high, but not all are prepared mentally for what it takes to it consistently enough to actually yield something significant.
I'm not a dealer, not in it purely for the profit either, but I choose to familiarize myself with the ins and outs of used camera sale, because that's the only way I know how to be able to afford what I want and still come up ahead in the end.
And after doing it several years, I managed to pretty much balance my GAS spending and strange thing is, now that I've put photography in the forefront, I own way less cameras than when I started a few years ago 🙂