Seller has not contacted yet. How long should I wait...

Wait another 5 minutes

Still a good question.  I have often wondered myself.   Thanks for putting it out there.   It's good to read others viewpoints and read experiences. 

... and we have contact!

A few weeks ago I did a Buy it Now, and the Audiogon system instructed me to wait for an invoice from the seller before making payment. When I didn't hear from him for a few days, I emailed telling him about Audiogons message to me, and asked for a total with shipping. Heard nothing for a few more days, but did eventually. I made payment, heard nothing about my payment having been received, but did get a tracking number and a thank you. Not how I do things, but I was raised right ;-). 

I recently  sold a unit that buyer had no feedback  and never communicate. 
Audiogone hold my funds on express checkout for 8 days after item was delivered since buyer did never said a word. 
Fortunately  happy ending I got my funds. 

Please do not get me wrong. I was not trying to "escalate" the issue. I was just curious about how long you guys normally wait before becoming concerned.

I fully realize he has a life. We all do.

I have to agree with what bdp24 said. You can't expect a seller to be as fast as Amazon. People have other priorities in life. I can't believe that due to the OP not hearing back from a seller in 12 hours you are ready to escalate. If it isn't a pro seller I'll give the person 2 business days before I inquire. If it is a pro seller I'll give them 1 business day.

Thank you guys for your time. I feel slightly better that I see a tracking number on the original listing here on the gon. It just seems funky to me that somebody, heck anybody, would engage in online transaction in this day and age, but not have any communication whatsoever.

I wanted to give him benefit of a doubt but I also needed to take action in a timely manner if necessary.

We shall see.  

It would have been nice to recieve a ’thank-you’ note or acknowledgement from the seller but from my experience not every one follows ’social’ etiquettes on this site.

I usually wait upto 48 hours before I hit the panic button :-)

Glad to hear your item on the way. Let’s hope there are no further issues with the merchandise.

Patience, grasshopper. 12 hours not very much time---the seller most likely has a job and family requiring his attention, the auction being a low priority. Nothing to worry about---yet.

I would flag it with Audiogon just to be safe.

Well It looks like the page containing the info for the item has been updated with tracking info. Still zero communication though.

Yes I paid via the express checkout.

Did you already pay for it, or just commit to the purchase? Please say that you didn't pay yet...