http://www.irs.gov/irs/article/0,,id=186056,00.html has some good information regarding hobby and/or business activities that we as CRH'ers might engage in.
Even as a hobbiest, you MIGHT be able to zero out your gain on a sale by virtue of the expenses (auto being a big one) you've racked up over time accumulating your sold loot. This is especially so if you have done a lot of driving to accumulate your stash.
If you are a big time sorter it might be to your benefit financially to establish yourself as a small business. You MIGHT be able to take a loss on your tax return, contribute to a retirement plan, etc.
Take note of the "MIGHT"'s in the previous paragraphs. There are only two sure things in life, death and TAXES, eveything else comes with strings attached. But, with a some record keeping, timing, and planning you might, at the very least, hold the taxman at bay for a bit.
Then again, you might take the tack a lot of people do. They figure they're small time, not on the radar screen, "so let them come to me." I'm not saying it's right, it's just the way it is.