You seriously think the IRS is going to go after you for an order on Overstock?
Do you feel responsible for all negative consequences caused by your tax dollars?
I've got other political enemies as well. If by "negative consequences of my tax dollars", you mean "things our governments spend money on that I disagree with"...no, I don't feel wholly responsible for them, since I fight the proponents of those things, too.
Items purchased online in NYS are subject to sales tax at the time of the transaction, and the burden is on the vendor to collect it.
Therefore, an Overstock order in Bitcoins could be a 'red flag' that causes the IRS to look into your other tax arrangements.