Is it double taxation?

As S7horton says, the tax isn't on the item, it's on the transaction.

I bought used stuff from audiogon but seller(s) never asked for sales tax. Never run across a listing in this web-site that the seller ask for sales tax up-front or back end. Do you? So what the difference between e-bay and audiogon?

Andrew--a private deal---betweeen private parties has no sales tx. Many dealers whom advertise here tell you up front in their ads---residents of their state will be charged tx.

As S7horton says, the tax isn't on the item, it's on the transaction.

The tax being charged though is probably the transaction taking place between the seller and ebay...

IF your state has a sales tax you ARE REQUIRED TO PAY IT.
If not when purchasing off the net, then when you file your taxes... They ASK for the money. (Of course whether you cough it up is your lying, cheating soul at stake...
(8^Q...
Then one wonders what the seller is doing asking for a sales tax. ??Maybe he has been 'hurt' in the past by the tax collectors and wants to be certain he covers his a$$.
Or, he may just want to add a bonus to his bottom line.. as I have NEVER heard of private indeviduals, or non 'in your own state' requirement to collect sales taxes.