If it's a private-party transanction in which the buyer sends a monoy order or paypal, the seller really should ship within 5 business days. I mean, why the hold up? You know you were going to sale the thing; get it ready to go!--or at least mention some anticipated delay in the copy of the for-sale ad. Unexpected delays in shipping are particularly irksome when you've just paid 2 or 3k for that BAT pre you've always wanted!
