You better check out the new CSPC Publication #254 for violations that you might commit selling your stuff to your fellow citizen:

This handbook will help sellers of used products identify types of potentially hazardous products that could harm children or others. CPSC’s laws and regulations apply to anyone who sells or distributes consumer products. This includes thrift stores, consignment stores, charities, and individuals holding yard sales and flea markets.

So you could be on the hook for thousands of dollars of fines if you sell something that the government has deemed hazardous. How in the heck do they think they’ll ever enforce this?
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