It happens when buying used,i rarely buy anything brand new.
A couple things to remember when buying used that will make the whole process easier to do,remember that most of the time your buying from a fellow hobbiest like yourself,a person with family & work obligations that come first,also unless you paid extra for saturday delievery then saturday & sunday dont count in shipping lag time,also be sure to account for the payment clearing the bank,even when paying with Paypal,what Paypal considers an instant payment for the buyer takes 2 to 3 business days to reach the sellers bank account,more & more sellers are waiting for Paypal to clear their account due to charge back scams from buyers.
Also try & remember that the older the peice of gear your buying the more chance of it being damaged in transit,sometimes all it takes to damage a peice of older gear is the shock of transit with no visible signs of damage to the box.
Patience is the key to finding good deals on used gear,its also the key to keeping your sanity durring the transaction.