After about 3 days, I'd try e-mailing again, in 
case the first mail was somehow lost. (If you 
haven't already done so.)
But much beyond then, and I think I'd give up.
Sometimes they've got a good, valid reason for 
taking so long (emergency, loss of internet 
access for a while,) so it might be worth it to 
wait a little longer.  I've had people take as 
much as a week to get back to me, either for eBay 
or other purchases, and things went smoothly from 
there.
On the other hand, I had a guy take 2 months to 
send me an e-mail just to say that he'd send me 
the e-mail about the auction "soon."
I got the 2nd e-mail asking for payment and 
giving me his address another month later.  ~.~  
Let's guess whether or not Mala bought from 
*that* guy any more..
I guess it all depends on the circumstances and 
the item.