I'm now in Manila and this is actually how most ebay transactions for high end items end up. I agree there are many legitimate reasons for wanting to pay in cash (get the bag ASAP, no worries about the post office, etc. etc) particularly if you are in the same city. I think performing the transaction at the bank sounds like a good idea. However, if you aren't comfortable and if you have no one to accompany you, you may be safer passing it up.