While I don't sell anything online I still handle every item a couple or more times personally but to me that's all par for the course and factored into my prices, just as every other overhead is, so I see no reason to charge any punter a handling fee on top of anything.

I can see what the OP is getting at and I have to agree with them because if you don't handle the gear you'll never hand it over to anyone at any time, and that means you never flog it off lol.